522 lines
16 KiB
JavaScript
522 lines
16 KiB
JavaScript
// Data distribution optimizer using linear programming (lp_solve)
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const child_process = require('child_process');
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const NO_OSD = 'Z';
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async function lp_solve(text)
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{
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const cp = child_process.spawn('lp_solve');
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let stdout = '', stderr = '', finish_cb;
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cp.stdout.on('data', buf => stdout += buf.toString());
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cp.stderr.on('data', buf => stderr += buf.toString());
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cp.on('exit', () => finish_cb && finish_cb());
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cp.stdin.write(text);
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cp.stdin.end();
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if (cp.exitCode == null)
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{
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await new Promise(ok => finish_cb = ok);
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}
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if (!stdout.trim())
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{
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return null;
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}
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let score = 0;
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let vars = {};
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for (const line of stdout.split(/\n/))
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{
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let m = /^(^Value of objective function: ([\d\.]+)|Actual values of the variables:)\s*$/.exec(line);
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if (m)
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{
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if (m[2])
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{
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score = m[2];
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}
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continue;
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}
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else if (/This problem is (infeasible|unbounded)/.exec(line))
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{
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return null;
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}
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let [ k, v ] = line.trim().split(/\s+/, 2);
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if (v)
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{
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vars[k] = v;
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}
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}
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return { score, vars };
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}
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async function optimize_initial(osd_tree, pg_count, max_combinations)
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{
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max_combinations = max_combinations || 10000;
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const all_weights = Object.assign({}, ...Object.values(osd_tree));
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const total_weight = Object.values(all_weights).reduce((a, c) => Number(a) + Number(c), 0);
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let all_pgs = all_combinations(osd_tree, null, true);
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if (all_pgs.length > max_combinations)
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{
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const prob = max_combinations/all_pgs.length;
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all_pgs = all_pgs.filter(pg => Math.random() < prob);
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}
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const pg_per_osd = {};
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for (const pg of all_pgs)
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{
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for (const osd of pg)
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{
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pg_per_osd[osd] = pg_per_osd[osd] || [];
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pg_per_osd[osd].push("pg_"+pg.join("_"));
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}
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}
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const pg_size = Math.min(Object.keys(osd_tree).length, 3);
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let lp = '';
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lp += "max: "+all_pgs.map(pg => 'pg_'+pg.join('_')).join(' + ')+";\n";
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for (const osd in pg_per_osd)
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{
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if (osd !== NO_OSD)
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{
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let osd_pg_count = all_weights[osd]/total_weight*pg_size*pg_count;
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lp += pg_per_osd[osd].join(' + ')+' <= '+osd_pg_count+';\n';
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}
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}
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for (const pg of all_pgs)
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{
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lp += 'pg_'+pg.join('_')+" >= 0;\n";
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}
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lp += "sec "+all_pgs.map(pg => 'pg_'+pg.join('_')).join(', ')+";\n";
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const lp_result = await lp_solve(lp);
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if (!lp_result)
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{
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throw new Error('Problem is infeasible or unbounded - is it a bug?');
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}
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const int_pgs = make_int_pgs(lp_result.vars, pg_count);
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const eff = pg_list_space_efficiency(int_pgs, all_weights);
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return { score: lp_result.score, weights: lp_result.vars, int_pgs, space: eff*pg_size, total_space: total_weight };
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}
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function make_int_pgs(weights, pg_count)
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{
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const total_weight = Object.values(weights).reduce((a, c) => Number(a) + Number(c), 0);
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let int_pgs = [];
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let pg_left = pg_count;
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let weight_left = total_weight;
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for (const pg_name in weights)
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{
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let n = Math.round(weights[pg_name] / weight_left * pg_left);
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for (let i = 0; i < n; i++)
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{
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int_pgs.push(pg_name.substr(3).split('_'));
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}
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weight_left -= weights[pg_name];
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pg_left -= n;
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}
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return int_pgs;
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}
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// Try to minimize data movement
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async function optimize_change(prev_int_pgs, osd_tree, max_combinations)
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{
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max_combinations = max_combinations || 10000;
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const pg_size = Math.min(Object.keys(osd_tree).length, 3);
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const pg_count = prev_int_pgs.length;
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const prev_weights = {};
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const prev_pg_per_osd = {};
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for (const pg of prev_int_pgs)
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{
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const pg_name = 'pg_'+pg.join('_');
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prev_weights[pg_name] = (prev_weights[pg_name]||0) + 1;
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for (const osd of pg)
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{
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prev_pg_per_osd[osd] = prev_pg_per_osd[osd] || [];
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prev_pg_per_osd[osd].push(pg_name);
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}
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}
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// Get all combinations
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let all_pgs = all_combinations(osd_tree, null, true);
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if (all_pgs.length > max_combinations)
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{
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const intersecting = all_pgs.filter(pg => prev_weights['pg_'+pg.join('_')]);
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if (intersecting.length > max_combinations)
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{
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const prob = max_combinations/intersecting.length;
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all_pgs = intersecting.filter(pg => Math.random() < prob);
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}
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else
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{
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const prob = (max_combinations-intersecting.length)/all_pgs.length;
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all_pgs = all_pgs.filter(pg => Math.random() < prob || prev_weights['pg_'+pg.join('_')]);
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}
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}
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const pg_per_osd = {};
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for (const pg of all_pgs)
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{
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const pg_name = 'pg_'+pg.join('_');
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for (const osd of pg)
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{
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pg_per_osd[osd] = pg_per_osd[osd] || [];
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pg_per_osd[osd].push(pg_name);
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}
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}
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// Penalize PGs based on their similarity to old PGs
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const intersect = {};
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for (const pg_name in prev_weights)
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{
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const pg = pg_name.substr(3).split(/_/);
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intersect[pg[0]+'::'] = intersect[':'+pg[1]+':'] = intersect['::'+pg[2]] = 2;
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intersect[pg[0]+'::'+pg[2]] = intersect[':'+pg[1]+':'+pg[2]] = intersect[pg[0]+':'+pg[1]+':'] = 1;
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}
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const move_weights = {};
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for (const pg of all_pgs)
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{
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move_weights['pg_'+pg.join('_')] =
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intersect[pg[0]+'::'+pg[2]] || intersect[':'+pg[1]+':'+pg[2]] || intersect[pg[0]+':'+pg[1]+':'] ||
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intersect[pg[0]+'::'] || intersect[':'+pg[1]+':'] || intersect['::'+pg[2]] ||
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3;
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}
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// Calculate total weight - old PG weights
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const all_pg_names = all_pgs.map(pg => 'pg_'+pg.join('_'));
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const all_weights = Object.assign({}, ...Object.values(osd_tree));
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const total_weight = Object.values(all_weights).reduce((a, c) => Number(a) + Number(c), 0);
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// Generate the LP problem
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let lp = '';
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lp += 'max: '+all_pg_names.map(pg_name => (
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prev_weights[pg_name] ? `${4-move_weights[pg_name]}*add_${pg_name} - 4*del_${pg_name}` : `${4-move_weights[pg_name]}*${pg_name}`
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)).join(' + ')+';\n';
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for (const osd in pg_per_osd)
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{
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if (osd !== NO_OSD)
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{
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const osd_sum = (pg_per_osd[osd]||[]).map(pg_name => prev_weights[pg_name] ? `add_${pg_name} - del_${pg_name}` : pg_name).join(' + ');
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const rm_osd_pg_count = (prev_pg_per_osd[osd]||[]).filter(old_pg_name => move_weights[old_pg_name]).length;
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let osd_pg_count = all_weights[osd]*3/total_weight*pg_count - rm_osd_pg_count;
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lp += osd_sum + ' <= ' + osd_pg_count + ';\n';
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}
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}
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let pg_vars = [];
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for (const pg_name of all_pg_names)
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{
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if (prev_weights[pg_name])
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{
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pg_vars.push(`add_${pg_name}`, `del_${pg_name}`);
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// Can't add or remove less than zero
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lp += `add_${pg_name} >= 0;\n`;
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lp += `del_${pg_name} >= 0;\n`;
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// Can't remove more than the PG already has
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lp += `add_${pg_name} - del_${pg_name} >= -${prev_weights[pg_name]};\n`;
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}
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else
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{
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pg_vars.push(pg_name);
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lp += `${pg_name} >= 0;\n`;
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}
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}
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lp += 'sec '+pg_vars.join(', ')+';\n';
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// Solve it
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const lp_result = await lp_solve(lp);
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if (!lp_result)
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{
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console.log(lp);
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throw new Error('Problem is infeasible or unbounded - is it a bug?');
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}
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// Generate the new distribution
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const weights = { ...prev_weights };
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for (const k in prev_weights)
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{
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if (!move_weights[k])
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{
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delete weights[k];
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}
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}
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for (const k in lp_result.vars)
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{
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if (k.substr(0, 4) === 'add_')
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{
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weights[k.substr(4)] = (weights[k.substr(4)] || 0) + Number(lp_result.vars[k]);
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}
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else if (k.substr(0, 4) === 'del_')
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{
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weights[k.substr(4)] = (weights[k.substr(4)] || 0) - Number(lp_result.vars[k]);
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}
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else
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{
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weights[k] = Number(lp_result.vars[k]);
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}
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}
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for (const k in weights)
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{
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if (!weights[k])
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{
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delete weights[k];
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}
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}
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const int_pgs = make_int_pgs(weights, pg_count);
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// Align them with most similar previous PGs
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const new_pgs = align_pgs(prev_int_pgs, int_pgs);
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let differs = 0, osd_differs = 0;
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for (let i = 0; i < pg_count; i++)
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{
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if (new_pgs[i].join('_') != prev_int_pgs[i].join('_'))
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{
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differs++;
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}
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for (let j = 0; j < 3; j++)
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{
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if (new_pgs[i][j] != prev_int_pgs[i][j])
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{
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osd_differs++;
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}
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}
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}
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return {
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prev_pgs: prev_int_pgs,
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score: lp_result.score,
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weights,
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int_pgs: new_pgs,
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differs,
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osd_differs,
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space: pg_size * pg_list_space_efficiency(new_pgs, all_weights),
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total_space: total_weight,
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};
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}
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function print_change_stats(retval, detailed)
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{
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const new_pgs = retval.int_pgs;
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const prev_int_pgs = retval.prev_pgs;
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if (prev_int_pgs)
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{
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if (detailed)
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{
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for (let i = 0; i < new_pgs.length; i++)
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{
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if (new_pgs[i].join('_') != prev_int_pgs[i].join('_'))
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{
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console.log("pg "+i+": "+prev_int_pgs[i].join(' ')+" -> "+new_pgs[i].join(' '));
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}
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}
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}
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console.log(
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"Data movement: "+retval.differs+" pgs, "+
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retval.osd_differs+" pg*osds = "+Math.round(retval.osd_differs / prev_int_pgs.length / 3 * 10000)/100+" %"
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);
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}
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console.log(
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"Total space (raw): "+Math.round(retval.space*100)/100+" TB, space efficiency: "+
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Math.round(retval.space/(retval.total_space||1)*10000)/100+" %"
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);
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}
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function align_pgs(prev_int_pgs, int_pgs)
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{
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const aligned_pgs = [];
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put_aligned_pgs(aligned_pgs, int_pgs, prev_int_pgs, (pg) => [ pg.join(':') ]);
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put_aligned_pgs(aligned_pgs, int_pgs, prev_int_pgs, (pg) => [ pg[0]+'::'+pg[2], ':'+pg[1]+':'+pg[2], pg[0]+':'+pg[1]+':' ]);
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put_aligned_pgs(aligned_pgs, int_pgs, prev_int_pgs, (pg) => [ pg[0]+'::', ':'+pg[1]+':', '::'+pg[2] ]);
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const free_slots = prev_int_pgs.map((pg, i) => !aligned_pgs[i] ? i : null).filter(i => i != null);
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for (const pg of int_pgs)
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{
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if (!free_slots.length)
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{
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throw new Error("Can't place unaligned PG");
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}
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aligned_pgs[free_slots.shift()] = pg;
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}
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return aligned_pgs;
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}
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function put_aligned_pgs(aligned_pgs, int_pgs, prev_int_pgs, keygen)
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{
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let prev_indexes = {};
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for (let i = 0; i < prev_int_pgs.length; i++)
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{
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for (let k of keygen(prev_int_pgs[i]))
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{
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prev_indexes[k] = prev_indexes[k] || [];
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prev_indexes[k].push(i);
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}
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}
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PG: for (let i = int_pgs.length-1; i >= 0; i--)
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{
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let pg = int_pgs[i];
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let keys = keygen(int_pgs[i]);
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for (let k of keys)
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{
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while (prev_indexes[k] && prev_indexes[k].length)
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{
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let idx = prev_indexes[k].shift();
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if (!aligned_pgs[idx])
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{
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aligned_pgs[idx] = pg;
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int_pgs.splice(i, 1);
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continue PG;
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}
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}
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}
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}
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}
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// Convert multi-level osd_tree = { level: number|string, id?: string, size?: number, children?: osd_tree }[]
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// levels = { string: number }
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// to a two-level osd_tree suitable for all_combinations()
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function flatten_tree(osd_tree, levels, failure_domain_level, osd_level, domains = {}, i = { i: 1 })
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{
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osd_level = levels[osd_level] || osd_level;
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failure_domain_level = levels[failure_domain_level] || failure_domain_level;
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for (const node of osd_tree)
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{
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if ((levels[node.level] || node.level) < failure_domain_level)
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{
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flatten_tree(node.children||[], levels, failure_domain_level, osd_level, domains, i);
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}
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else
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{
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domains['dom'+(i.i++)] = extract_osds([ node ], levels, osd_level);
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}
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}
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return domains;
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}
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function extract_osds(osd_tree, levels, osd_level, osds = {})
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{
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for (const node of osd_tree)
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{
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if ((levels[node.level] || node.level) >= osd_level)
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{
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osds[node.id] = node.size;
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}
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else
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{
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extract_osds(node.children||[], levels, osd_level, osds);
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}
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}
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return osds;
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}
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// FIXME: support different pg_sizes, not just 3
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// osd_tree = { failure_domain1: { osd1: size1, ... }, ... }
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function all_combinations(osd_tree, count, ordered)
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{
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const hosts = Object.keys(osd_tree).sort();
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const osds = Object.keys(osd_tree).reduce((a, c) => { a[c] = Object.keys(osd_tree[c]).sort(); return a; }, {});
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while (hosts.length < 3)
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{
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osds[NO_OSD] = [ NO_OSD ];
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hosts.push(NO_OSD);
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}
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let host_idx = [ 0, 1, 2 ];
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let osd_idx = [ 0, 0, 0 ];
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const r = [];
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while (!count || count < 0 || r.length < count)
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{
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let inc;
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if (host_idx[2] != host_idx[1] && host_idx[2] != host_idx[0] && host_idx[1] != host_idx[0])
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{
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r.push(host_idx.map((hi, i) => osds[hosts[hi]][osd_idx[i]]));
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inc = 2;
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while (inc >= 0)
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{
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osd_idx[inc]++;
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if (osd_idx[inc] >= osds[hosts[host_idx[inc]]].length)
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{
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osd_idx[inc] = 0;
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inc--;
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}
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else
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{
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break;
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}
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}
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}
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else
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{
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inc = -1;
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}
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if (inc < 0)
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{
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// no osds left in current host combination, select the next one
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osd_idx = [ 0, 0, 0 ];
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host_idx[2]++;
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if (host_idx[2] >= hosts.length)
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{
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host_idx[1]++;
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host_idx[2] = ordered ? host_idx[1]+1 : 0;
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if ((ordered ? host_idx[2] : host_idx[1]) >= hosts.length)
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{
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host_idx[0]++;
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host_idx[1] = ordered ? host_idx[0]+1 : 0;
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host_idx[2] = ordered ? host_idx[1]+1 : 0;
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if ((ordered ? host_idx[2] : host_idx[0]) >= hosts.length)
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{
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break;
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}
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}
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}
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}
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}
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return r;
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}
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function pg_weights_space_efficiency(weights, pg_count, osd_sizes)
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{
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const per_osd = {};
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for (const pg_name in weights)
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{
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for (const osd of pg_name.substr(3).split(/_/))
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{
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per_osd[osd] = (per_osd[osd]||0) + weights[pg_name];
|
|
}
|
|
}
|
|
return pg_per_osd_space_efficiency(per_osd, pg_count, osd_sizes);
|
|
}
|
|
|
|
function pg_list_space_efficiency(pgs, osd_sizes)
|
|
{
|
|
const per_osd = {};
|
|
for (const pg of pgs)
|
|
{
|
|
for (const osd of pg)
|
|
{
|
|
per_osd[osd] = (per_osd[osd]||0) + 1;
|
|
}
|
|
}
|
|
return pg_per_osd_space_efficiency(per_osd, pgs.length, osd_sizes);
|
|
}
|
|
|
|
function pg_per_osd_space_efficiency(per_osd, pg_count, osd_sizes)
|
|
{
|
|
// each PG gets randomly selected in 1/N cases
|
|
// & there are x PGs per OSD
|
|
// => an OSD is selected in x/N cases
|
|
// => total space * x/N <= OSD size
|
|
// => total space <= OSD size * N/x
|
|
let space;
|
|
for (let osd in per_osd)
|
|
{
|
|
if (osd in osd_sizes)
|
|
{
|
|
const space_estimate = osd_sizes[osd] * pg_count / per_osd[osd];
|
|
if (space == null || space > space_estimate)
|
|
{
|
|
space = space_estimate;
|
|
}
|
|
}
|
|
}
|
|
return space == null ? 0 : space;
|
|
}
|
|
|
|
module.exports = {
|
|
NO_OSD,
|
|
|
|
optimize_initial,
|
|
optimize_change,
|
|
print_change_stats,
|
|
pg_weights_space_efficiency,
|
|
pg_list_space_efficiency,
|
|
pg_per_osd_space_efficiency,
|
|
flatten_tree,
|
|
|
|
lp_solve,
|
|
make_int_pgs,
|
|
align_pgs,
|
|
all_combinations,
|
|
};
|