From: Linus Torvalds <torvalds@linux-foundation.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked
Date: Fri, 4 Nov 2016 08:59:15 -0700 [thread overview]
Message-ID: <CA+55aFxoT82RocOCZ9+k7_NZ+KZNtCQrwzNd=reB0n03xDj4-A@mail.gmail.com> (raw)
In-Reply-To: <20161104182942.47c4d544@roar.ozlabs.ibm.com>
On Fri, Nov 4, 2016 at 12:29 AM, Nicholas Piggin <npiggin@gmail.com> wrote:
> Oh, okay, the zone lookup. Well I am of the impression that most of the
> cache misses are coming from the waitqueue hash table itself.
No.
Nick, stop this idiocy.
NUMBERS, Nick. NUMBERS.
I posted numbers in "page_waitqueue() considered harmful" on linux-mm.
And quite frankly, before _you_ start posting numbers, that zone crap
IS NEVER COMING BACK.
What's so hard about this concept? We don't add crazy complexity
without numbers. Numbers that I bet you will not be able to provide,
because quiet frankly, even in your handwavy "what about lots of
concurrent IO from hundreds of threads" situation, that wait-queue
will NOT BE NOTICEABLE.
So no "impressions". No "what abouts". No "threaded IO" excuses. The
_only_ thing that matters is numbers. If you don't have them, don't
bother talking about that zone patch.
Linus
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-11-04 15:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-02 7:03 [RFC][PATCH 0/2] optimise unlock_page / end_page_writeback Nicholas Piggin
2016-11-02 7:03 ` [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Nicholas Piggin
2016-11-04 2:20 ` Hugh Dickins
2016-11-11 0:58 ` Nicholas Piggin
2016-11-02 7:03 ` [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked Nicholas Piggin
2016-11-02 7:31 ` Kirill A. Shutemov
2016-11-02 7:50 ` Nicholas Piggin
2016-11-02 7:58 ` Kirill A. Shutemov
2016-11-02 8:12 ` Nicholas Piggin
2016-11-02 8:33 ` Kirill A. Shutemov
2016-11-02 8:40 ` Nicholas Piggin
2016-11-02 9:04 ` Kirill A. Shutemov
2016-11-02 15:18 ` Linus Torvalds
2016-11-03 3:46 ` Nicholas Piggin
2016-11-03 15:49 ` Linus Torvalds
2016-11-04 2:40 ` Nicholas Piggin
2016-11-04 7:29 ` Nicholas Piggin
2016-11-04 15:59 ` Linus Torvalds [this message]
2016-11-07 3:04 ` Nicholas Piggin
2016-11-04 2:31 ` [lkp] [mm] 731b9bc419: kernel BUG at include/linux/page-flags.h:259! kernel test robot
2016-11-04 2:47 ` Nicholas Piggin
2016-12-21 15:19 [PATCH 0/2] respin of PageWaiters patch Nicholas Piggin
2016-12-21 15:19 ` [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked Nicholas Piggin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CA+55aFxoT82RocOCZ9+k7_NZ+KZNtCQrwzNd=reB0n03xDj4-A@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=jack@suse.cz \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox