On Mon, Aug 28, 2006 at 02:40:38PM +0000, Arn?r Kristj?nsson wrote: > Hi, > > I'm running a vserver running various LAMP servers. A while ago I > installed munin to check how the server was behaving at various > times. It turns out that the server has a LOT of iowait (up to 115) > when under load. > > What I did was that I ran tiobench on the local HD and this is what I > got: > -- > Sequential Reads > File Blk Num > Avg Maximum Lat% Lat% CPU > Identifier Size Size Thr Rate (CPU%) > Latency Latency >2s >10s Eff > ---------------------------- ------ ----- --- ------ ------ > --------- ----------- -------- -------- ----- > 2.6.14.3-vs2.0.1 100 4096 1 446.29 99.97% > 0.006 0.04 0.00000 0.00000 446 > 2.6.14.3-vs2.0.1 100 4096 2 728.70 396.4% > 0.007 0.05 0.00000 0.00000 184 > 2.6.14.3-vs2.0.1 100 4096 4 855.43 1587.% > 0.011 0.20 0.00000 0.00000 54 > 2.6.14.3-vs2.0.1 100 4096 8 839.09 2328.% > 0.013 56.08 0.00000 0.00000 36 > > Random Reads > File Blk Num > Avg Maximum Lat% Lat% CPU > Identifier Size Size Thr Rate (CPU%) > Latency Latency >2s >10s Eff > ---------------------------- ------ ----- --- ------ ------ > --------- ----------- -------- -------- ----- > 2.6.14.3-vs2.0.1 100 4096 1 418.79 96.48% > 0.006 0.02 0.00000 0.00000 434 > 2.6.14.3-vs2.0.1 100 4096 2 754.47 386.3% > 0.006 0.04 0.00000 0.00000 195 > 2.6.14.3-vs2.0.1 100 4096 4 839.15 1374.% > 0.010 0.05 0.00000 0.00000 61 > 2.6.14.3-vs2.0.1 100 4096 8 739.47 870.8% > 0.009 0.04 0.00000 0.00000 85 > > Sequential Writes > File Blk Num > Avg Maximum Lat% Lat% CPU > Identifier Size Size Thr Rate (CPU%) > Latency Latency >2s >10s Eff > ---------------------------- ------ ----- --- ------ ------ > --------- ----------- -------- -------- ----- > 2.6.14.3-vs2.0.1 100 4096 1 6.89 4.602% > 0.021 9.83 0.00000 0.00000 150 > 2.6.14.3-vs2.0.1 100 4096 2 9.12 15.32% > 0.031 80.06 0.00000 0.00000 60 > 2.6.14.3-vs2.0.1 100 4096 4 9.65 52.36% > 0.040 0.54 0.00000 0.00000 18 > 2.6.14.3-vs2.0.1 100 4096 8 9.92 102.5% > 0.066 100.08 0.00000 0.00000 10 > > Random Writes > File Blk Num > Avg Maximum Lat% Lat% CPU > Identifier Size Size Thr Rate (CPU%) > Latency Latency >2s >10s Eff > ---------------------------- ------ ----- --- ------ ------ > --------- ----------- -------- -------- ----- > 2.6.14.3-vs2.0.1 100 4096 1 0.34 0.148% > 0.010 0.03 0.00000 0.00000 230 > 2.6.14.3-vs2.0.1 100 4096 2 0.34 0.352% > 0.011 0.06 0.00000 0.00000 98 > 2.6.14.3-vs2.0.1 100 4096 4 0.37 1.033% > 0.017 0.07 0.00000 0.00000 36 > 2.6.14.3-vs2.0.1 100 4096 8 0.38 1.596% > 0.016 0.14 0.00000 0.00000 24 > -- > > I'm wondering; shouldn't the CPU % be lower on reads?
well, I'm not sure what that data is trying to tell us, because something like 2300 % CPU usage does not sound like a sensible value to me, unless you have something like 32 processors in that machine ... > Is there a way to increase this performance? sure, get better/faster disks, smarter controllers, faster bus interfaces between cpu and i/o cards ... sometimes even fine tuning of existing hardware can make a big difference, like using the proper driver with the 'right' options and/or avoiding partitions which block disk access (when used simultaiously) really depends on the setup HTH, Herbert > A. > _______________________________________________ > Vserver mailing list > [email protected] > http://list.linux-vserver.org/mailman/listinfo/vserver _______________________________________________ Vserver mailing list [email protected] http://list.linux-vserver.org/mailman/listinfo/vserver
