Hi, Just found a strange things happened on my FC4/FC5 boxes: around 90% CPU times are wasted in disk I/O wait when I doing a simple "dd if=/dev/sdb of=/dev/null >/dev/null 2>&1 &" test. vmstat shows the CPU cycles when there are I/O waiting. And at these times ssh sessions and keyboard response is pretty slow. On old FC1 and Redhat 9 I did't see this problem, I configured 2.4 kernels to accept other Interrupts during disk I/O to for much beter interactive responses. How can I do it again on 2.6 kernels? The following is my test results. Please have a look and help. [root@testnode01 ~]# vmstat 2 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 1 0 160 29792 2626332 556320 0 0 1849 18 695 148 1 1 96 2 0 0 160 29304 2626368 556284 0 0 110 42 286 47 14 0 83 3 0 0 160 34880 2626396 550100 0 0 156 44 289 68 9 2 84 5 [root@testnode01 ~]# dd if=/dev/sdc of=/dev/null 2>&1 & [1] 9933 [root@testnode01 ~]# vmstat 2 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 1 2 160 20284 2747752 441056 0 0 1853 18 694 148 1 1 96 2 0 1 160 20496 2865276 321480 0 0 59062 0 499 530 11 13 0 77 0 1 160 20604 2981924 202780 0 0 58496 46 493 518 4 13 0 83 0 1 160 20508 3099396 83256 0 0 59008 24 499 528 3 14 0 83 0 1 160 21372 3156688 23912 0 0 59008 0 497 519 4 13 0 83 [root@testnode01 ~]# cat /proc/loadavg 0.51 0.23 0.10 2/84 9937 [root@testnode01 ~]# uname -a Linux testnode01.example.com 2.6.15.6_64_v3tcp #1 SMP Fri Mar 17 16:59:19 PST 2006 x86_64 x86_64 x86_64 GNU/Linux [root@testnode01 ~]# cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 3 model name : Intel(R) Pentium(R) 4 CPU 3.60GHz stepping : 4 cpu MHz : 3600.302 cache size : 1024 KB fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall lm constant_tsc pni monitor ds_cpl cid xtpr bogomips : 7211.15 clflush size : 64 cache_alignment : 128 address sizes : 36 bits physical, 48 bits virtual power management: __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
