* Re: [patch 63/87] md: define raid5_mergeable_bvec
[not found] ` <20061211090301.GH4576@kernel.dk>
@ 2006-12-11 10:04 ` Raz Ben-Jehuda(caro)
2006-12-11 10:08 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Raz Ben-Jehuda(caro) @ 2006-12-11 10:04 UTC (permalink / raw)
To: Jens Axboe; +Cc: Linux Kernel
[-- Attachment #1: Type: text/plain, Size: 2215 bytes --]
this is against 2.6.19-git17
hope this correct
raz
On 12/11/06, Jens Axboe <jens.axboe@oracle.com> wrote:
> On Mon, Dec 11 2006, Raz Ben-Jehuda(caro) wrote:
> > On 12/11/06, Jens Axboe <jens.axboe@oracle.com> wrote:
> > >On Sun, Dec 10 2006, akpm@osdl.org wrote:
> > >> From: "Raz Ben-Jehuda(caro)" <raziebe@gmail.com>
> > >>
> > >> This will encourage read request to be on only one device, so we will
> > >often be
> > >> able to bypass the cache for read requests.
> > >>
> > >> Signed-off-by: Neil Brown <neilb@suse.de>
> > >> Cc: Jens Axboe <jens.axboe@oracle.com>
> > >> Signed-off-by: Andrew Morton <akpm@osdl.org>
> > >> ---
> > >>
> > >> drivers/md/raid5.c | 24 ++++++++++++++++++++++++
> > >> 1 file changed, 24 insertions(+)
> > >>
> > >> diff -puN drivers/md/raid5.c~md-define-raid5_mergeable_bvec
> > >drivers/md/raid5.c
> > >> --- a/drivers/md/raid5.c~md-define-raid5_mergeable_bvec
> > >> +++ a/drivers/md/raid5.c
> > >> @@ -2611,6 +2611,28 @@ static int raid5_congested(void *data, i
> > >> return 0;
> > >> }
> > >>
> > >> +/* We want read requests to align with chunks where possible,
> > >> + * but write requests don't need to.
> > >> + */
> > >> +static int raid5_mergeable_bvec(request_queue_t *q, struct bio *bio,
> > >struct bio_vec *biovec)
> > >> +{
> > >> + mddev_t *mddev = q->queuedata;
> > >> + sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
> > >> + int max;
> > >> + unsigned int chunk_sectors = mddev->chunk_size >> 9;
> > >> + unsigned int bio_sectors = bio->bi_size >> 9;
> > >> +
> > >> + if (bio_data_dir(bio))
> > >> + return biovec->bv_len; /* always allow writes to be
> > >mergeable */
> > >
> > >Please don't ever do that - you are making assumptions on the value of
> > >READ and WRITE.
> > >
> > > if (bio_data_dir(bio) == WRITE)
> > > ...
> > >
> > >If this has already been merged, please submit a patch correcting it.
> > >People end up copying code like this :-)
> > >
> > >--
> > >Jens Axboe
> > >
> > >
> >
> > thanks Jens
> > the attached is a fix.
>
> But the patch is already merged, so the patch needs to be against Linus'
> current tree.
>
> --
> Jens Axboe
>
>
--
Raz
[-- Attachment #2: mergeablevecJens.patch --]
[-- Type: text/x-patch, Size: 487 bytes --]
--- linux-2.6.19/drivers/md/raid5.c 2006-12-11 11:33:23.000000000 +0000
+++ linux-2.6.19-git17/drivers/md/raid5.c 2006-12-11 11:31:27.000000000 +0000
@@ -2567,7 +2567,7 @@
unsigned int chunk_sectors = mddev->chunk_size >> 9;
unsigned int bio_sectors = bio->bi_size >> 9;
- if (bio_data_dir(bio))
+ if (bio_data_dir(bio) == WRITE )
return biovec->bv_len; /* always allow writes to be mergeable */
max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
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