Messages in this thread | | | Date | Sat, 20 Jan 2007 21:09:17 +0100 | From | Willy Tarreau <> | Subject | Re: Abysmal disk performance, how to debug? |
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On Sat, Jan 20, 2007 at 02:56:20PM -0500, Stephen Clark wrote: > Sunil Naidu wrote: > > >On 1/20/07, Willy Tarreau <w@1wt.eu> wrote: > > > > > >>It is not expected to increase write performance, but it should help > >>you do something else during that time, or also give more responsiveness > >>to Ctrl-C. It is possible that you have fast and slow RAM, or that your > >>video card uses shared memory which slows down some parts of memory > >>which are not used anymore with those parameters. > >> > >> > > > >I did test some SATA drives, am getting these value for 2.6.20-rc5:- > > > >[sukhoi@Typhoon ~]$ time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 > >1024+0 records in > >1024+0 records out > >1073741824 bytes (1.1 GB) copied, 21.0962 seconds, 50.9 MB/s > > > >What can you suggest here w.r.t my RAM & disk? > > > > > > > >>Willy > >> > >> > > > >Thanks, > > > >~Akula2 > >- > >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/ > > > > > > > Hi, > whitebook vbi s96f core 2 duo t5600 2gb hitachi ATA HTS721060G9AT00 > using libata > time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 > 1024+0 records in > 1024+0 records out > 1073741824 bytes (1.1 GB) copied, 10.0092 seconds, 107 MB/s > > real 0m10.196s > user 0m0.004s > sys 0m3.440s
You have too much RAM, it's possible that writes did not complete before the end of your measurement. Try this instead :
$ time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024 | sync
Willy
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