| *siege -c 5 -b -t30s http://drupal/* ** SIEGE 2.67 ** Preparing 5 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 927 hits Availability: 100.00 % Elapsed time: 29.76 secs Data transferred: 2.21 MB Response time: *0.16 secs* Transaction rate: *31.15 trans/sec* Throughput: 0.07 MB/sec Concurrency: 4.96 Successful transactions: 927 Failed transactions: 0 Longest transaction: 2.05 Shortest transaction: 0.03]]> |0077aa|~>| *vmstat 1* procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy *id* wa 7 0 297704 333808 103644 680204 0 0 0 32 278 1682 90 10 *0* 0 5 0 297704 333184 103644 680348 0 0 0 0 279 1668 94 6 *0* 0 6 0 297704 333516 103644 680500 0 0 0 0 269 1701 92 8 *0* 0 6 0 297704 333076 103644 680612 0 0 0 0 266 1651 93 8 *0* 0 15 0 297704 333780 103644 680640 0 0 0 0 274 1718 93 7 *0* 0 6 0 297704 332248 103652 681548 0 0 0 32 328 2519 86 14 *0* 0 5 0 297704 329704 103652 684272 0 0 0 0 286 1623 90 11 *0* 0 7 0 297704 330208 103652 684184 0 0 0 0 374 1793 93 7 *0* 0 7 0 297704 332452 103652 681164 0 0 0 0 268 1678 95 6 *0* 0 7 0 297704 332196 103652 681460 0 0 0 0 291 1667 93 7 *0* 0 6 0 297704 332336 103660 681484 0 0 0 20 278 1718 92 8 *0* 0 6 0 297704 333412 103660 680792 0 0 0 0 279 1655 91 9 *0* 0 The cpu *id*le column is 0, and the io *wa*it is 0. If you have *id*>10 and *wa*>10 then you are likely io-bound and you need to track down your io issues instead of worrying about PHP.