lkml.org 
[lkml]   [2007]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] mm - background_writeout exits when pages_skipped ?
On Thu, Oct 11, 2007 at 06:19:34PM +0100, richard kennedy wrote:
> When background_writeout() (mm/page-writeback.c) finds any pages_skipped
> in writeback_inodes() and it didn't meet any congestion, it exits even
> when it hasn't written enough pages yet.
>
> Performing 2 ( or more) concurrent copies of a large file, often creates
> lots of skipped pages (1000+) making background_writeout exit and so
> pages don't get written out until we reach dirty_ratio.
>
> I added some instrumentation to fs/buffer.c in
> __block_write_full_page(..) and all the skipped pages come from here :-
>
> done:
> if (nr_underway == 0) {
> /*
> * The page was marked dirty, but the buffers were
> * clean. Someone wrote them back by hand with
> * ll_rw_block/submit_bh. A rare case.
> */
> end_page_writeback(page);
>
> /*
> * The page and buffer_heads can be released at any time from
> * here on.
> */

> wbc->pages_skipped++; /* We didn't write this page */

FYI: The above line has just been removed in 2.6.23-mm1, which fixed the bug.

Thank you,
Fengguang

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-10-14 13:13    [W:0.039 / U:0.600 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site