Messages in this thread | ![/](/images/icornerl.gif) | | From | "Vitezslav Samel" <> | Date | Tue, 1 Apr 2003 14:16:53 +0200 | Subject | Re: [IDE SiI680] throughput drop to 1/4 |
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On Wed, Mar 26, 2003 at 07:56:50AM +0100, Vitezslav Samel wrote: > On Tue, Mar 25, 2003 at 08:06:05AM +0100, Vitezslav Samel wrote: > > On Mon, Mar 24, 2003 at 07:13:06AM -0500, Alan Cox wrote: > > > > Recently I tried to figure out in 2.5.65, why throughput on my disk which > > > > hangs on Silicon Image 680 dropped to 1/4 compared to 2.4.21-pre5, but didn't > > > > found anything useful. Are there any known issues with this driver? > > > > > > The same code in both cases. Its quite likely the problem is higher up in > > > the block or filesystem layer. It might also be a general IDE layer bug > > > > > > What does performance look like on your other disk between > > > 2.4.21pre/2.5.65 ? > > > > Will test it as I come back home (it's on my home machine). But I think this > > performance drop is only on the SiI680 interface. > > Tested today: on the other disk on integrated interface (piix) is throughput > exactly the same on both kernels.
I put my eyes on /etc/rc.d/* and found hdparm doing some magic; then I tried to fiddle with its params and came to this: the problem lied in fs readahead (hdparm -a xxx). Tried various numbers:
fs readahead throughput in 2.5.66 throughput in 2.4.21-pre6 ----------------------------------------------------------------- 0 11.94 MB/sec 40.00 MB/sec 8 12.01 MB/sec 38.79 MB/sec 16 12.04 MB/sec 40.25 MB/sec 24 15.22 MB/sec 39.51 MB/sec 32 15.17 MB/sec 40.00 MB/sec 40 15.20 MB/sec 39.02 MB/sec 48 15.26 MB/sec 40.00 MB/sec 56 17.60 MB/sec 40.25 MB/sec 64 16.03 MB/sec 40.00 MB/sec 64 15.95 MB/sec 40.25 MB/sec 72 17.32 MB/sec 40.00 MB/sec 80 18.34 MB/sec 40.25 MB/sec 88 18.72 MB/sec 40.25 MB/sec 96 16.04 MB/sec 39.26 MB/sec 104 16.68 MB/sec 40.25 MB/sec 112 18.25 MB/sec 39.02 MB/sec 120 18.42 MB/sec 40.00 MB/sec 128 19.17 MB/sec 39.26 MB/sec 136 26.67 MB/sec 40.00 MB/sec 144 39.31 MB/sec 39.51 MB/sec 152 39.58 MB/sec 39.75 MB/sec 160 39.68 MB/sec 40.25 MB/sec 168 39.98 MB/sec 40.25 MB/sec 176 39.85 MB/sec 40.51 MB/sec 184 40.18 MB/sec 40.00 MB/sec
So I disabled setting fs readahead (the default values are O.K.). Seems like setting fs readahead doesn't make any change on 2.4 kernels.
Cheers, Vita - 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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