From: Andrew Morton <akpm@osdl.org>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: nickpiggin@yahoo.com.au, marcelo.tosatti@cyclades.com,
linux-kernel@vger.kernel.org
Subject: Re: [pagevec] resize pagevec to O(lg(NR_CPUS))
Date: Mon, 13 Sep 2004 19:57:31 -0700 [thread overview]
Message-ID: <20040913195731.28dcc2e3.akpm@osdl.org> (raw)
In-Reply-To: <20040914021844.GN9106@holomorphy.com>
William Lee Irwin III <wli@holomorphy.com> wrote:
>
> William Lee Irwin III <wli@holomorphy.com> wrote:
> >> A large stream of faults to map in a file will blow L1 caches of the
> >> sizes you've mentioned at every kernel/user context switch. 256 distinct
> >> cachelines will very easily be referenced between faults. MAP_POPULATE
> >> and mlock() don't implement batching for either ->page_table_lock or
> >> ->tree_lock, so the pagevec point is moot in pagetable instantiation
> >> codepaths (though it probably shouldn't be).
>
> On Sun, Sep 12, 2004 at 12:42:56AM -0700, Andrew Morton wrote:
> > Instantiation via normal fault-in becomes lock-intensive once you have
> > enough CPUs. At low CPU count the page zeroing probably preponderates.
>
> But that's mm->page_table_lock, for which pagevecs aren't used,
It is zone->lru_lock and pagevecs are indeed used. See
do_anonymous_page->lru_cache_add_active.
> On Sun, Sep 12, 2004 at 12:42:56AM -0700, Andrew Morton wrote:
> > Possibly. I wouldn't bother converting anything unless a profiler tells
> > you to though.
>
> mlock() is the case I have in hand, though I've only heard of it being
> problematic on vendor kernels. MAP_POPULATE is underutilized in
> userspace thus far, so I've not heard anything about it good or bad.
>
If you're referring to mlock() of an anonymous vma then that should all go
through do_anonymous_page->lru_cache_add_active anyway?
next prev parent reply other threads:[~2004-09-14 3:02 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-09 16:39 [PATCH] cacheline align pagevec structure Marcelo Tosatti
2004-09-09 22:49 ` Andrew Morton
2004-09-09 21:41 ` Marcelo Tosatti
2004-09-09 23:20 ` Andrew Morton
2004-09-09 22:52 ` Andrew Morton
2004-09-09 23:09 ` William Lee Irwin III
2004-09-09 22:12 ` Marcelo Tosatti
2004-09-09 23:59 ` William Lee Irwin III
2004-09-09 23:22 ` Andrew Morton
2004-09-10 0:07 ` [pagevec] resize pagevec to O(lg(NR_CPUS)) William Lee Irwin III
2004-09-10 4:56 ` Nick Piggin
2004-09-10 4:59 ` Nick Piggin
2004-09-10 17:49 ` Marcelo Tosatti
2004-09-12 0:29 ` Nick Piggin
2004-09-12 5:23 ` William Lee Irwin III
2004-09-12 4:36 ` Nick Piggin
2004-09-12 4:56 ` William Lee Irwin III
2004-09-12 4:28 ` Nick Piggin
2004-09-12 6:27 ` William Lee Irwin III
2004-09-12 6:03 ` Nick Piggin
2004-09-12 7:19 ` William Lee Irwin III
2004-09-12 7:42 ` Andrew Morton
2004-09-14 2:18 ` William Lee Irwin III
2004-09-14 2:57 ` Andrew Morton [this message]
2004-09-14 3:12 ` William Lee Irwin III
2004-09-12 8:57 ` William Lee Irwin III
2004-09-13 22:21 ` Marcelo Tosatti
2004-09-14 1:59 ` Nick Piggin
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