Messages in this thread | | | Date | Sat, 4 Apr 2009 08:57:28 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [GIT PULL] Ext3 latency fixes |
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On Sat, 4 Apr 2009, Jens Axboe wrote: > > Big nack on this patch. Ted, this is EXACTLY where I told you we saw big > write regressions (sqlite performance drops by a factor of 4-5). Do a > git log on fs/buffer.c and see the original patch (which does what your > patch does) and the later revert. No idea why you are now suggestion > making that exact change?!
Jens, if I can re-create the 'fsync' times (I haven't yet), then the default scheduler _will_ be switched to AS.
> Low latency is nice, but not at the cost of 4-5x throughput for real > world cases.
I'm sorry, but that fsync thing _is_ a real-world case, and it's the one that a hell of a lot more people care about than some idiotic sqlite throughput issue.
You have a test-case now. Consider it a priority, or consider CFQ to be a "for crazy servers that only care about throughput".
Quite frankly, the fact that I can see _seconds_ of latencies with a really good SSD is not acceptable. The fact that it is by design is even less so.
Latency is more important than throughput. It's that simple.
Linus
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