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Date: Fri, 4 Oct 2013 15:31:47 -0500
From: Alex Thorlton <athorlton@....com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
Al Viro <viro@...iv.linux.org.uk>,
Andi Kleen <ak@...ux.intel.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Dave Hansen <dave.hansen@...el.com>,
Dave Jones <davej@...hat.com>,
David Howells <dhowells@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Johannes Weiner <hannes@...xchg.org>,
Kees Cook <keescook@...omium.org>,
Mel Gorman <mgorman@...e.de>,
Michael Kerrisk <mtk.manpages@...il.com>,
Oleg Nesterov <oleg@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Rik van Riel <riel@...hat.com>,
Robin Holt <robinmholt@...il.com>,
Sedat Dilek <sedat.dilek@...il.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv4 00/10] split page table lock for PMD tables
On Fri, Oct 04, 2013 at 11:26:02PM +0300, Kirill A. Shutemov wrote:
> Alex Thorlton wrote:
> > Kirill,
> >
> > I've pasted in my results for 512 cores below. Things are looking
> > really good here. I don't have a test for HUGETLBFS, but if you want to
> > pass me the one you used, I can run that too. I suppose I could write
> > one, but why reinvent the wheel? :)
>
> Patch below.
Good deal, thanks. I'll get some test results put up soon.
>
> > Sorry for the delay on these results. I hit some strange issues with
> > running thp_memscale on systems with either of the following
> > combinations of configuration options set:
> >
> > [thp off]
> > HUGETLBFS=y
> > HUGETLB_PAGE=y
> > NUMA_BALANCING=y
> > NUMA_BALANCING_DEFAULT_ENABLED=y
> >
> > [thp on or off]
> > HUGETLBFS=n
> > HUGETLB_PAGE=n
> > NUMA_BALANCING=y
> > NUMA_BALANCING_DEFAULT_ENABLED=y
> >
> > I'm getting segfaults intermittently, as well as some weird RCU sched
> > errors. This happens in vanilla 3.12-rc2, so it doesn't have anything
> > to do with your patches, but I thought I'd let you know. There didn't
> > used to be any issues with this test, so I think there's a subtle kernel
> > bug here. That's, of course, an entirely separate issue though.
>
> I'll take a look next week, if nobody does it before.
I'm starting a bisect now. Not sure how long it'll take, but I'll keep
you posted.
>
> >
> > As far as these patches go, I think everything looks good (save for the
> > bit of discussion you were having with Andrew earlier, which I think
> > you've worked out). My testing shows that the page fault rates are
> > actually better on this threaded test than in the non-threaded case!
> >
> > - Alex
> >
> > THP on, v3.12-rc2:
> > ------------------
> >
> > Performance counter stats for './thp_memscale -C 0 -m 0 -c 512 -b 512m' (5 runs):
> >
> > 568668865.944994 task-clock # 528.547 CPUs utilized ( +- 0.21% ) [100.00%]
> > 1,491,589 context-switches # 0.000 M/sec ( +- 0.25% ) [100.00%]
> > 1,085 CPU-migrations # 0.000 M/sec ( +- 1.80% ) [100.00%]
> > 400,822 page-faults # 0.000 M/sec ( +- 0.41% )
> > 1,306,612,476,049,478 cycles # 2.298 GHz ( +- 0.23% ) [100.00%]
> > 1,277,211,694,318,724 stalled-cycles-frontend # 97.75% frontend cycles idle ( +- 0.21% ) [100.00%]
> > 1,163,736,844,232,064 stalled-cycles-backend # 89.07% backend cycles idle ( +- 0.20% ) [100.00%]
> > 53,855,178,678,230 instructions # 0.04 insns per cycle
> > # 23.72 stalled cycles per insn ( +- 1.15% ) [100.00%]
> > 21,041,661,816,782 branches # 37.002 M/sec ( +- 0.64% ) [100.00%]
> > 606,665,092 branch-misses # 0.00% of all branches ( +- 0.63% )
> >
> > 1075.909782795 seconds time elapsed ( +- 0.21% )
> >
> > THP on, patched:
> > ----------------
> >
> > Performance counter stats for './runt -t -c 512 -b 512m' (5 runs):
> >
> > 15836198.490485 task-clock # 533.304 CPUs utilized ( +- 0.95% ) [100.00%]
> > 127,507 context-switches # 0.000 M/sec ( +- 1.65% ) [100.00%]
> > 1,223 CPU-migrations # 0.000 M/sec ( +- 3.23% ) [100.00%]
> > 302,080 page-faults # 0.000 M/sec ( +- 6.88% )
> > 18,925,875,973,975 cycles # 1.195 GHz ( +- 0.43% ) [100.00%]
> > 18,325,469,464,007 stalled-cycles-frontend # 96.83% frontend cycles idle ( +- 0.44% ) [100.00%]
> > 17,522,272,147,141 stalled-cycles-backend # 92.58% backend cycles idle ( +- 0.49% ) [100.00%]
> > 2,686,490,067,197 instructions # 0.14 insns per cycle
> > # 6.82 stalled cycles per insn ( +- 2.16% ) [100.00%]
> > 944,712,646,402 branches # 59.655 M/sec ( +- 2.03% ) [100.00%]
> > 145,956,565 branch-misses # 0.02% of all branches ( +- 0.88% )
> >
> > 29.694499652 seconds time elapsed ( +- 0.95% )
> >
> > (these results are from the test suite that I ripped thp_memscale out
> > of, but it's the same test)
>
> 36 times faster. Not bad I think. ;)
>
> Naive patch to use HUGETLB:
>
> --- thp_memscale/thp_memscale.c 2013-09-23 23:44:21.000000000 +0300
> +++ thp_memscale/thp_memscale.c 2013-09-26 17:45:47.878429885 +0300
> @@ -191,7 +191,10 @@
> int id, i, cnt;
>
> id = (long)arg;
> - p = malloc(bytes);
> + p = mmap(NULL, bytes, PROT_READ | PROT_WRITE,
> + MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, 0, 0);
> + if (p == MAP_FAILED)
> + perrorx("mmap failed");
> ps = p;
>
> if (runon(basecpu + id) < 0)
> --
> Kirill A. Shutemov
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