Messages in this thread | | | Date | Tue, 11 Apr 2006 21:49:11 +0200 | From | "Alessandro Suardi" <> | Subject | Re: 40% IDE performance regression going from FC3 to FC5 with same kernel |
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On 4/11/06, Jan Engelhardt <jengelh@linux01.gwdg.de> wrote: > >> > I'll be filing a FC5 performance bug for this but would like an opinion > >> > from the IDE kernel people just in case this has already been seen... > >> > > >> > I just upgraded my home K7-800, 512MB RAM box from FC3 to FC5 > >> > and noticed a disk performance slowdown while copying files around. > >> > >> Just another suggestion: try eliminating/pinpointing I/O scheduler issues > >> (switch e.g. to "noop" at /sys/block/hda/queue/scheduler and compare again) > > > >Thanks Andi. Tried every scheduler (my default is anticipatory) and > > there aren't meaningful differences - 18.3 to 18.6MB/s. > > > >As a further data point, my box can burn a 8x DVD+R at up to 7.1x > > average speed under FC3, while it barely keeps up with 4x in FC5. > > Since you said it happens with the same kernel, I think it's caused by > userspace (do the boot-with-"-b" thing and you'll know). Possible someone > setting DMA to speeds as low as udma4 or udma2.
Booting into /sbin/init -b indeed shows I get 33.3MB/s from hdparm, as in FC3. DMA is (again according to hdparm) udma4 both booted normally and in emergency mode. Note that at this point I'm testing 2.6.17-rc1-git4 in FC5, not to be trailing current kernels too much (and yes, I already tested that normal 2.6.17-rc1-git4 boot in FC5 gets 18.5MB/s - without IDE_GENERIC, so that is also clearly a non relevant factor).
As per Bill Davidsen's question in another email, blockdev --getra shows 256, which is the same value that hdparm shows.
--alessandro
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