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Date: Sat, 20 Jan 2007 22:16:15 +0200 From: Ismail Dönmez <ismail@...dus.org.tr> To: Tim Schmielau <tim@...sik3.uni-rostock.de> Cc: Willy Tarreau <w@....eu>, linux-kernel@...r.kernel.org Subject: Re: Abysmal disk performance, how to debug? 20 Oca 2007 Cts 22:10 tarihinde, Tim Schmielau şunları yazmıştı: [...] > > Note that these dd "benchmarks" are completely bogus, because the data=20 > doesn't actually get written to disk in that time. For some enlightening=20 > data, try > > time dd if=3D/dev/zero of=3D/tmp/1GB bs=3D1M count=3D1024; time sync > > The dd returns as soon as all data could be buffered in RAM. Only sync=20 > will show how long it takes to actually write out the data to disk. > also explains why you see better results is writeout starts earlier. Still not that bad: [~]> time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024;sync 1024+0 records in 1024+0 records out 1073741824 bytes (1,1 GB) copied, 53,3194 s, 20,1 MB/s real 0m53.517s user 0m0.003s sys 0m3.193s - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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