Dual-CPU Waits with high idle percentage
Serge Dubrouski
sergeyfd at gmail.com
Fri Jun 15 22:11:15 UTC 2007
The root cause for "slow SSH logins" could be ssh inability to do
reverse DNS lookups on clients IP addresses.
On 6/15/07, Young, Mike <Mike.Young at atosorigin.com> wrote:
> Hello,
>
> I'm troubleshooting some slow performance on a RHEL ES4 build. Problem is "slow SSH logins". None of the usual configuration culprits are at fault (kernel configs, name resolution, PAM modules, network config). I started running vmstat and found that I was getting CPU waits at high idle times, on a dual-CPU system. Anyway, here's the output of vmstat - let me know if anything strikes you as odd.
>
> Thanks,
> Mike.
>
> bash-3.00# vmstat 5
> procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 0 0 32 68208 335840 6276452 0 0 1 41 3 1 1 0 99 0
> 0 1 32 68208 335840 6276452 0 0 0 26 1095 346 0 0 100 0
> 0 0 32 66440 335840 6276452 0 0 0 52 1080 491 0 0 98 1
> 1 0 32 67640 335840 6276452 0 0 0 122 1123 854 10 1 88 1
> 0 0 32 67664 335840 6276452 0 0 0 166 1078 497 5 0 95 0
> 0 0 32 67736 335840 6276452 0 0 0 19 1093 331 0 0 99 1
> 0 0 32 67744 335840 6276452 0 0 0 0 1066 334 7 0 93 0
> 0 0 32 67728 335840 6276452 0 0 0 21 1096 383 1 0 98 1
> 0 0 32 67728 335840 6276452 0 0 0 18 1066 309 0 0 100 0
> 0 0 32 67744 335840 6276452 0 0 0 36 1098 353 0 0 100 1
> 0 0 32 67760 335840 6276452 0 0 0 6 1070 341 0 0 99 0
> 0 0 32 67760 335840 6276452 0 0 0 32 1106 344 0 0 100 0
> 0 0 32 67728 335840 6276452 0 0 0 46 1074 332 0 0 100 0
> 0 0 32 67728 335840 6276452 0 0 0 5 1094 344 0 0 99 0
> 0 0 32 67712 335840 6276452 0 0 0 25 1082 378 0 0 99 0
> 0 0 32 67352 335844 6276584 0 0 0 30 1126 445 1 0 99 0
> 0 0 32 66584 335864 6277380 0 0 10 130 1117 403 2 0 97 1
> 0 0 32 66608 335864 6277380 0 0 0 239 1119 533 1 0 98 1
> 0 0 32 66344 335864 6277380 0 0 0 155 1081 369 8 0 91 1
> 0 0 32 66216 335868 6277444 0 0 0 87 1101 337 1 0 99 0
> 0 0 32 66160 335872 6277576 0 0 0 0 1069 314 0 0 100 0
> 0 0 32 66224 335872 6277644 0 0 0 51 1092 490 37 1 61 0
> 0 0 32 66088 335876 6277640 0 0 0 53 1069 322 0 0 99 1
> 1 0 32 61464 335892 6279120 0 0 0 53 1148 439 3 0 96 1
> 0 0 32 59864 335896 6280544 0 0 0 636 1103 342 0 0 98 1
> 0 0 32 58888 335896 6280680 0 0 0 53 1160 1005 14 1 84 1
> 0 0 32 58824 335896 6280748 0 0 0 48 1073 332 1 0 99 0
> 0 0 32 58432 335896 6280748 0 0 0 186 1115 392 2 0 97 1
> 0 1 32 58304 335900 6280948 0 0 0 98 1098 480 2 0 97 1
> 0 0 32 55680 335900 6281016 0 0 0 226 1165 492 1 0 98 1
> 0 0 32 55624 335900 6281016 0 0 0 54 1074 386 8 0 92 0
> 0 1 32 56232 335900 6281016 0 0 0 148 1121 384 1 0 97 2
> 0 0 32 57520 335900 6281016 0 0 0 66 1066 327 0 0 99 1
> 0 0 32 58624 335900 6281016 0 0 0 18 1094 438 0 0 99 0
> 0 0 32 58424 335904 6281148 0 0 0 36 1095 363 1 0 99 0
> 0 0 32 58368 335912 6281276 0 0 0 78 1101 335 0 0 99 1
> 0 0 32 73344 335664 6266496 0 0 0 30 1069 381 24 1 76 0
> 0 0 32 74504 335664 6266496 0 0 0 53 1098 447 27 1 72 1
> 0 0 32 74568 335664 6266496 0 0 0 71 1070 313 0 0 99 1
> 1 0 32 73584 335664 6266496 0 0 0 86 1110 393 1 0 98 1
> 0 0 32 73008 335664 6266496 0 0 0 47 1123 834 10 0 89 1
> 0 0 32 72296 335664 6266496 0 0 0 246 1120 399 1 0 98 1
> 0 0 32 72296 335664 6266496 0 0 0 5 1065 332 7 0 93 0
> 0 0 32 72040 335664 6266496 0 0 0 3 1090 348 1 0 99 0
> 0 0 32 72040 335664 6266496 0 0 0 3 1073 305 0 0 100 0
>
>
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--
Serge Dubrouski.
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