From: Andrea Arcangeli <aarcange@redhat.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Arthur Marsh <arthur.marsh@internode.on.net>,
Clemens Ladisch <cladisch@googlemail.com>,
Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm: compaction: Minimise the time IRQs are disabled while isolating pages for migration
Date: Sat, 26 Feb 2011 01:16:11 +0100 [thread overview]
Message-ID: <20110226001611.GA19630@random.random> (raw)
In-Reply-To: <20110225223204.GW25382@cmpxchg.org>
On Fri, Feb 25, 2011 at 11:32:04PM +0100, Johannes Weiner wrote:
> I don't understand why this conditional is broken up like this.
> cond_resched() will have the right checks anyway. Okay, you would
> save fatal_signal_pending() in the 'did one cluster' case. Is it that
> expensive? Couldn't this be simpler like
>
> did_cluster = ((low_pfn + 1) % SWAP_CLUSTER_MAX) == 0
> lock_contended = spin_is_contended(&zone->lru_lock);
> if (did_cluster || lock_contended || need_resched()) {
> spin_unlock_irq(&zone->lru_lock);
> cond_resched();
> spin_lock_irq(&zone->lru_lock);
> if (fatal_signal_pending(current))
> break;
> }
>
> instead?
If we don't release irqs first, how can need_resched get set in the
first place if the local apic irq can't run? I guess that's why
there's no cond_resched_lock_irq. BTW, I never liked too much clearing
interrupts for locks that can't ever be taken from irq (it's a
scalability boost to reduce contention but it makes things like above
confusing and it increases irq latency a bit.
--
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/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-02-26 0:16 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-25 20:04 [PATCH 0/2] Reduce the amount of time compaction disables IRQs for V2 Mel Gorman
2011-02-25 20:04 ` [PATCH 1/2] mm: compaction: Minimise the time IRQs are disabled while isolating free pages Mel Gorman
2011-02-25 22:34 ` Johannes Weiner
2011-02-28 1:55 ` KAMEZAWA Hiroyuki
2011-02-28 22:08 ` Minchan Kim
2011-02-25 20:04 ` [PATCH 2/2] mm: compaction: Minimise the time IRQs are disabled while isolating pages for migration Mel Gorman
2011-02-25 22:32 ` Johannes Weiner
2011-02-26 0:16 ` Andrea Arcangeli [this message]
2011-02-28 2:17 ` KAMEZAWA Hiroyuki
2011-02-28 5:48 ` Andrea Arcangeli
2011-02-28 5:54 ` KAMEZAWA Hiroyuki
2011-02-28 9:28 ` Mel Gorman
2011-02-28 9:42 ` KAMEZAWA Hiroyuki
2011-02-28 10:18 ` Mel Gorman
2011-02-28 23:42 ` KAMEZAWA Hiroyuki
2011-03-01 4:11 ` Minchan Kim
2011-03-01 4:49 ` KAMEZAWA Hiroyuki
2011-02-28 23:01 ` Minchan Kim
2011-02-28 23:07 ` Andrea Arcangeli
2011-02-28 23:25 ` Minchan Kim
2011-03-01 22:15 ` Andrew Morton
2011-02-25 20:07 ` [PATCH 0/2] Reduce the amount of time compaction disables IRQs for V2 Andrea Arcangeli
-- strict thread matches above, loose matches on Subject: below --
2011-03-01 15:35 [PATCH 2/2] mm: compaction: Minimise the time IRQs are disabled while isolating pages for migration Minchan Kim
2011-03-01 16:19 ` Andrea Arcangeli
2011-03-01 22:22 ` Minchan Kim
2011-03-01 22:34 ` Andrew Morton
2011-03-01 22:57 ` Minchan Kim
2011-02-25 18:00 [PATCH 0/2] Reduce the amount of time compaction disables IRQs for Mel Gorman
2011-02-25 18:00 ` [PATCH 2/2] mm: compaction: Minimise the time IRQs are disabled while isolating pages for migration Mel Gorman
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=20110226001611.GA19630@random.random \
--to=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=arthur.marsh@internode.on.net \
--cc=cladisch@googlemail.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mel@csn.ul.ie \
/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;
as well as URLs for NNTP newsgroup(s).