Date: Wed, 12 Mar 2008 16:42:39 +1300 From: Mark Kirkwood <markir@paradise.net.nz> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-performance@freebsd.org Subject: Re: pgbench results Message-ID: <47D7512F.5020006@paradise.net.nz> In-Reply-To: <47D71F6F.2090600@paradise.net.nz> References: <fr33lg$tdu$1@ger.gmane.org> <571396.91912.qm@web50512.mail.re2.yahoo.com> <fr6at8$tpm$1@ger.gmane.org> <47D71F6F.2090600@paradise.net.nz>
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Mark Kirkwood wrote: > Ivan Voras wrote: >> >> The thing is - I *do* have a similar setup here: HP DL370 G5, 2x4-core >> 1.86 GHz, 4 GB RAM, 6 drives in RAID10, 512 MB cache (can pull > 200 >> MB/s off the array), with all settings like in the posted link except >> shared_buffer=1900 MB, and I "only" get this: >> >> tps = 2834.026175 (including connections establishing) >> tps = 2839.080739 (excluding connections establishing) >> >> This is still far bellow ~~ 4500 trans/s from the link and I wonder if >> my results are within what I should be getting. The benchmark in the >> link above was done with faster CPUs (but I'm not CPU bound - at least >> 30% idle), but with 3 times the memory and I'm guessing more memory >> would help here, but I'm not sure. >> >> What's strange is that toggling synchronous_commit doesn't have a >> significant effect on performance (it does increase CPU idle time). With >> synchronous_commit=off, I get: >> >> tps = 2886.980477 (including connections establishing) >> tps = 2891.776081 (excluding connections establishing) >> >> > > The article refers to a controller with a battery backed write cache - > that could easily explain the difference if you do not have one (he's > paying nothing for fsync wheres you are). > Hmm - somehow read right past the bit where you say you have a 512MB cache - sorry! However, worth checking it is set to write-back rather than write-through. Cheers Mark
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