From: "Stephen C. Tweedie" <sct@redhat.com>
To: Roger Larsson <roger.larsson@norran.net>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: User mode stalls - can it be...?
Date: Wed, 5 Jul 2000 14:35:19 +0100 [thread overview]
Message-ID: <20000705143519.D1290@redhat.com> (raw)
In-Reply-To: <39628F72.4987A36@norran.net>; from roger.larsson@norran.net on Wed, Jul 05, 2000 at 03:29:22AM +0200
Hi,
On Wed, Jul 05, 2000 at 03:29:22AM +0200, Roger Larsson wrote:
>
> static void sync_page_buffers(struct buffer_head *bh, int wait)
> {
> struct buffer_head * tmp = bh;
>
> do {
> struct buffer_head *p = tmp;
> tmp = tmp->b_this_page;
> if (!buffer_locked(p) &&
> buffer_dirty(p))
> ll_rw_block(WRITE, 1, &p);
> if (wait)
> __wait_on_buffer(p);
> } while (tmp != bh);
Yikes no. That will make the syncer wait for every single write
synchronously. It will cause a page full of 1k buffers to be written
out as four separate 1k writes instead of being streamed. This will
_kill_ performance.
Cheers,
Stephen
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next prev parent reply other threads:[~2000-07-05 13:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-07-05 0:54 Roger Larsson
2000-07-05 1:29 ` Roger Larsson
2000-07-05 13:35 ` Stephen C. Tweedie [this message]
2000-07-05 19:26 ` Roger Larsson
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