Messages in this thread | | | Subject | Re: 2.6.0 performance problems | From | Martin Schlemmer <> | Date | Tue, 30 Dec 2003 01:14:45 +0200 |
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On Tue, 2003-12-30 at 00:58, Thomas Molina wrote: > On Mon, 29 Dec 2003, Linus Torvalds wrote: > > > > > > > On Mon, 29 Dec 2003, Thomas Molina wrote: > > > > > > I just finished a couple of comparisons between 2.4 and 2.6 which seem to > > > confirm my impressions. I understand that the comparison may not be > > > apples to apples and my methods of testing may not be rigorous, but here > > > it is. In contrast to some recent discussions on this list, this test is > > > a "real world" test at which 2.6 comes off much worse than 2.4. > > > > Are you sure you have DMA enabled on your laptop disk? Your 2.6.x system > > times are very high - much bigger than the user times. That sounds like > > PIO to me. > > It certainly looks like DMA is enabled. Under 2.4 I get: > > [root@lap root]# hdparm /dev/hda > > /dev/hda: > multcount = 16 (on) > IO_support = 1 (32-bit) > unmaskirq = 1 (on) > using_dma = 1 (on) > keepsettings = 0 (off) > readonly = 0 (off) > readahead = 8 (on) > geometry = 2584/240/63, sectors = 39070080, start = 0 > > > Under 2.6 I get: > > [root@lap root]# hdparm /dev/hda > > /dev/hda: > multcount = 16 (on) > IO_support = 1 (32-bit) > unmaskirq = 1 (on) > using_dma = 1 (on) > keepsettings = 0 (off) > readonly = 0 (off) > readahead = 256 (on) > geometry = 38760/16/63, sectors = 39070080, start = 0 >
Increase your readahead:
# hdparm -a 8192 /dev/hda
BTW: As we really do get this question a _lot_ of times, why don't the ide layer automatically set a higher readahead if there is enough cache on the drive or something?
Thanks,
-- Martin Schlemmer [unhandled content-type:application/pgp-signature] | |