Messages in this thread | | | Date | Thu, 23 Dec 2004 12:26:48 +0530 | From | Paramveer Singh <> | Subject | 2.4.21 opteron 32 Gig RAM has 10k block writes/sec on running posgresql 7.4.6 disk i/o intensive app |
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we are using a RedHat AS3 U3 box (2.4.21-4.ELsmp) to run a very intensive database app which does a _huge_ number of inserts durnig the data generation phase. However, we are noticing a unexpected performance drops with user cpu utilization numbers falling to near 0.
most of the cpu is used up in iowait. CPU states: cpu user nice system irq softirq iowait idle total 2.0% 0.0% 7.6% 0.0% 0.0% 362.4% 27.2%
/proc/slabinfo showed huge numbers in buffer_head. The line was: buffer_head 4908452 4962249 200 260854 261171 1 : 16000 4000
some lines from vmstat 1 procs memory swap io system cpu r b swpd free buff cache si so bi bo in cs us sy wa id 4 2 10104 8585908 109820 19090508 0 0 37 1160 282 1421 8 4 67 22 1 4 10104 8585908 109824 19090684 0 0 0 4940 1359 4762 4 1 42 52 0 3 10104 8585908 109824 19091084 0 0 0 5296 1442 17178 13 4 40 43 8 1 10104 8585908 109824 19092068 0 0 0 2856 1437 34481 33 6 30 32 1 3 10104 8585908 109832 19093620 0 0 0 9012 1538 28554 35 7 34 25 0 3 10104 8585908 109832 19094004 0 0 0 6120 1552 3059 6 2 47 45 0 3 10104 8585908 109836 19094012 0 0 0 6188 1502 332 0 0 70 30 0 3 10104 8585908 109836 19094020 0 0 0 6436 1548 865 0 1 67 32 2 3 10104 8585908 109836 19094332 0 0 0 5980 1404 9322 10 3 52 36 0 3 10104 8585908 109840 19094332 0 0 0 5252 1492 190 0 0 74 25
Interestingly, the swap is not being used at all free output: Swap: 2040212 10104 2030108
the box is Quad AMD Opteron 1.8Ghz Tyan Mother board S4882UG2NR with Rack Chassis, 12 X 1 Hot swap bays, power supply + RPS Support 32Gb DDr sdram @ 266 8 X 80Gb SATA Hot Swap Hard Drive, 7200 RPM Adaptec SATA RAID controller
I tried to google but found some kswapd related bugs in AS3 which were fixed in U3. We upgraded even though this does not seem to be a kswapd error. I am gussing I have used some inappropriate numbers while setting up the box.
Would someone be kind to point me in a direction where I can find more information?
thanks a lot! ps - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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