Messages in this thread | | | From | Marc-Christian Petersen <> | Subject | Re: 2.4.20: Proccess stuck in __lock_page ... | Date | Tue, 27 May 2003 20:35:33 +0200 |
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On Tuesday 27 May 2003 20:25, Andrea Arcangeli wrote:
Hi Andrea,
> not exactly decreases I/O throughput, the latest I/O benchmarks I seen it decreases performance. I've seen this, Con also saw this (well it's better than the 'nr_requests = 4' change ;) but mouse stops are still there.
> from Randy (dbench/tiotest/bonnie/etc..) were still the fastest and it > included the lowlatency elevator patch. So it may not help latency but > it doesn't hurt in the numbers, at least not in the high end (that in > theory is the one that needs the overkill length in the I/O queue most). I agree with the last sentence, in theory, but practice showed something different (about 10% to 15% performance decrease)
But I am quite sure that this depends on your machine/hardware. Using IDE instead of SCSI for example.
> However it definitely helps latency for me and I had a number of > positive reports. It helps but it's not as good as 2.4.18 stock.
> Also make sure that you elvtune -r 0 -w 0 /dev/hda, also the journaling I also tried that.
> may affect the latency so you can try with plain ext2 to be sure it's > not a fs issue. Sure, I did this too. FS independent, where ReiserFS is still the best for this scenario with the most few pauses than any other FS (ext2, ext3, ...)
But for desktop usage: not acceptable! No way, No go!
> the lowlatency elevator patch may not be perfect but it definitely seems > to work better here. especially since there's no apparent throughput > loss, it makes lots of sense to keep it applied, or it would waste lots > of ram for apparently no gain. hehe, well wasting RAM for no gain is my next part on my todo ;) (cache everything even if there is no RAM for example, well but this is not the point in this thread)
ciao, Marc
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