Messages in this thread | | | From | Bill Davidsen <> | Subject | Re: [GIT PULL] adaptive spinning mutexes | Date | Fri, 16 Jan 2009 13:37:10 -0500 |
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Chris Mason wrote: > On Thu, 2009-01-15 at 10:16 -0800, Linus Torvalds wrote: >> On Thu, 15 Jan 2009, Ingo Molnar wrote: >>> btw., i think spin-mutexes have a design advantage here: in a lot of code >>> areas it's quite difficult to use spinlocks - cannot allocate memory, >>> cannot call any code that can sporadically block (but does not _normally_ >>> block), etc. >>> >>> With mutexes those atomicity constraints go away - and the performance >>> profile should now be quite close to that of spinlocks as well. >> Umm. Except if you wrote the code nicely and used spinlocks, you wouldn't >> hold the lock over all those unnecessary and complex operations. >> > > While this is true, there are examples of places we should expect > speedups for this today. > > Concurrent file creation/deletion in a single dir will often find things > hot in cache and not have to block anywhere (mail spools). > And although not as common, NNTP servers using file per article storage.
> Concurrent O_DIRECT aio writes to the same file, where i_mutex is > dropped early on. > > pipes should see a huge improvement. > I'd like to see that. Didn't realize how slow pipes really are.
> I'll kick off some runs of my three benchmarks on ext3 for comparison. > If there are things less synthetic people would like to see, please let > me know. > > -chris > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
-- Bill Davidsen <davidsen@tmr.com> "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot
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