Messages in this thread | | | Date | Tue, 9 Dec 2008 09:57:50 -0800 | Subject | Re: [RFC v2][PATCH]page_fault retry with NOPAGE_RETRY | From | Ying Han <> |
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Andrew, if it sounds good to include this patch in -mm at this point?
thanks
--Ying
On Sun, Dec 7, 2008 at 5:43 PM, Ying Han <yinghan@google.com> wrote: > Thanks Török for your experiment and that sounds great ! > > --Ying > > On Sat, Dec 6, 2008 at 1:55 AM, Török Edwin <edwintorok@gmail.com> wrote: >> On 2008-12-06 11:52, Török Edwin wrote: >>> On 2008-12-05 21:40, Ying Han wrote: >>> >>>> changelog[v2]: >>>> - reduce the runtime overhead by extending the 'write' flag of >>>> handle_mm_fault() to indicate the retry hint. >>>> - add another two branches in filemap_fault with retry logic. >>>> - replace find_lock_page with find_lock_page_retry to make the code >>>> cleaner. >>>> >>>> todo: >>>> - there is potential a starvation hole with the retry. By the time the >>>> retry returns, the pages might be released. we can make change by holding >>>> page reference as well as remembering what the page "was"(in case the >>>> file was truncated). any suggestion here are welcomed. >>>> >>>> I also made patches for all other arch. I am posting x86_64 here first and >>>> i will post others by the time everyone feels comfortable of this patch. >>>> >>>> Edwin, please test this patch with your testcase and check if you get any >>>> performance improvement of mmap over read. I added another two more places >>>> in filemap_fault with retry logic which you might hit in your privous >>>> experiment. >>>> >>>> >>> >>> I get much better results with this patch than with v1, thanks! >>> >>> mmap now scales almost as well as read does (there is a small ~5% >>> overhead), which is a significant improvement over not scaling at all! >>> >>> Here are the results when running my testcase: >>> >>> Number of threads ->, 1,,, 2,,, 4,,, 8,,, 16 >>> Kernel version, read, mmap, mixed, read, mmap, mixed, read, mmap, mixed, >>> read, mmap, mixed, read, mmap, mixed >>> 2.6.28-rc7-tip, 27.55, 26.18, 27.06, 16.18, 16.97, 16.10, 11.06, 11.64, >>> 11.41, 9.38, 9.97, 9.31, 9.37, 9.82, 9.3 >>> >>> >>> Here are the /proc/lock_stat output when running my testcase, contention >>> is lower (34911+10462 vs 58590+7231), and waittime-total is better >>> (57 601 464 vs 234 170 024) >>> >>> lock_stat version 0.3 >>> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>> class name con-bounces contentions >>> waittime-min waittime-max waittime-total acq-bounces >>> acquisitions holdtime-min holdtime-max holdtime-total >>> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>> &mm->mmap_sem-W: 5843 >>> 10462 2.89 138824.72 14217159.52 >>> 18965 84205 1.81 5031.07 725293.65 >>> &mm->mmap_sem-R: 20208 >>> 34911 4.87 136797.26 57601464.49 55797 >>> 1110394 1.89 164918.52 30551371.71 >>> --------------- >>> &mm->mmap_sem 5341 >>> [<ffffffff802bf9d7>] sys_munmap+0x47/0x80 >>> &mm->mmap_sem 28579 >>> [<ffffffff805d1c62>] do_page_fault+0x172/0xab0 >>> &mm->mmap_sem 5030 >>> [<ffffffff80211161>] sys_mmap+0xf1/0x140 >>> &mm->mmap_sem 6331 >>> [<ffffffff802a675e>] find_lock_page_retry+0xde/0xf0 >>> --------------- >>> &mm->mmap_sem 13558 >>> [<ffffffff802a675e>] find_lock_page_retry+0xde/0xf0 >>> &mm->mmap_sem 4694 >>> [<ffffffff802bf9d7>] sys_munmap+0x47/0x80 >>> &mm->mmap_sem 3681 >>> [<ffffffff80211161>] sys_mmap+0xf1/0x140 >>> &mm->mmap_sem 23374 >>> [<ffffffff805d1c62>] do_page_fault+0x172/0xab0 >>> >>> >>> On clamd: >>> >>> Here holdtime-total is better (1 493 154 + 2 395 987 vs 2 087 538 + 2 >>> 514 673), and number of contentions on read >>> (458 052 vs 5851 >> >> typo, should have been: 458 052 vs 585 119 >> >> > -- 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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