Messages in this thread | | | Date | Tue, 6 Mar 2001 11:02:37 -0500 (EST) | From | Jeremy Hansen <> |
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Ahh, now we're getting somewhere.
IDE:
jeremy:~# time ./xlog file.out fsync
real 0m33.739s user 0m0.010s sys 0m0.120s
so now this corresponds to the performance we're seeing on SCSI.
So I guess what I'm wondering now is can or should anything be done about this on the SCSI side?
Thanks -jeremy
On Tue, 6 Mar 2001, Mike Black wrote:
> Write caching is the culprit for the performance diff: > > On IDE: > time xlog /blah.dat fsync > 0.000u 0.190s 0:01.72 11.0% 0+0k 0+0io 91pf+0w > # hdparm -W 0 /dev/hda > > /dev/hda: > setting drive write-caching to 0 (off) > # time xlog /blah.dat fsync > 0.000u 0.220s 0:50.60 0.4% 0+0k 0+0io 91pf+0w > # hdparm -W 1 /dev/hda > > /dev/hda: > setting drive write-caching to 1 (on) > # time xlog /blah.dat fsync > 0.010u 0.230s 0:01.88 12.7% 0+0k 0+0io 91pf+0w > > On my SCSI setup: > # time xlog /usr5/blah.dat fsync > 0.020u 0.230s 0:30.48 0.8% 0+0k 0+0io 91pf+0w > > > ________________________________________ > Michael D. Black Principal Engineer > mblack@csihq.com 321-676-2923,x203 > http://www.csihq.com Computer Science Innovations > http://www.csihq.com/~mike My home page > FAX 321-676-2355 > ----- Original Message ----- > From: "Andre Hedrick" <andre@linux-ide.org> > To: "Linus Torvalds" <torvalds@transmeta.com> > Cc: "Douglas Gilbert" <dougg@torque.net>; <linux-kernel@vger.kernel.org> > Sent: Tuesday, March 06, 2001 2:12 AM > Subject: Re: scsi vs ide performance on fsync's > > > On Mon, 5 Mar 2001, Linus Torvalds wrote: > > > Well, it's fairly hard for the kernel to do much about that - it's almost > > certainly just IDE doing write buffering on the disk itself. No OS > > involved. > > I am pushing for WC to be defaulted in the off state, but as you know I > have a bigger fight than caching on my hands... > > > I don't know if there is any way to turn of a write buffer on an IDE disk. > > You want a forced set of commands to kill caching at init? > > Andre Hedrick > Linux ATA Development > ASL Kernel Development > ---------------------------------------------------------------------------- > - > ASL, Inc. Toll free: 1-877-ASL-3535 > 1757 Houret Court Fax: 1-408-941-2071 > Milpitas, CA 95035 Web: www.aslab.com > > - > 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/ > > - > 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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