On 04/23/2013 10:28 AM, Jinpu Wang wrote: > Hi Kent, > > I tested your patch today, it works well, and you're right, my patch > limits every BIO in a single page:( > > Thanks for your patch and share. > > Regards, > Jack > > > On Tue, Apr 23, 2013 at 7:12 AM, Jack Wang <jinpu.wang@xxxxxxxxxxxxxxxx > <mailto:jinpu.wang@xxxxxxxxxxxxxxxx>> wrote: > > On 2013年04月22日 23:46, Kent Overstreet wrote: > > On Wed, Apr 17, 2013 at 09:36:11AM +0200, Jack Wang wrote: > >> We are using your bcache-testing branch. > >> > >> From 20ad8cfb8047df2d09a5a960610f02c555a31a4f Mon Sep 17 00:00:00 > 2001 > >> From: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxxx > <mailto:jinpu.wang@xxxxxxxxxxxxxxxx>> > >> Date: Tue, 16 Apr 2013 14:59:04 +0200 > >> Subject: [PATCH] limit the max sectors in bcache to fix the make > request bug > >> in raid10 > >> During test bcache with raid1+0, we saw a lot of complain as below: > >> [ 2766.555172] md/raid0:md400: make_request bug: can't convert block > >> across chunks or bigger than 512k 953328 144 > >> > >> when the using dd or fio with bigger blocksize like 512k, limited the > >> bio_max_sectors resolve this issue. > > > > The fix is wrong - it'll have the effect of limiting _every_ bio > bcache > > emits to a single page, which will be bad for performance. > > > > I think I just found the problem though - looking at the raid0 > > merge_bvec_fn, when it's stacked on top of devices with their own > > merge_bvec_fns, it reuses the bvm was passed to it and modifies the > > bi_bdev and bi_sector. Ew. > > > > Can you try this patch and see if it fixes it? > Sure, thanks for looking into it, will test it today. > > > > commit a09ded8edf9ed4009930713e101249084cbcea5c > > Author: Kent Overstreet <koverstreet@xxxxxxxxxx > <mailto:koverstreet@xxxxxxxxxx>> > > Date: Mon Apr 22 14:44:24 2013 -0700 > > > > bcache: Fix merge_bvec_fn usage for when it modifies the bvm > > > > Stacked md devices reuse the bvm for the subordinate device, > causing > > problems... > > > > Reported-by: Michael Balser <michael.balser@xxxxxxxxxxxxxxxx > <mailto:michael.balser@xxxxxxxxxxxxxxxx>> > > Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx > <mailto:koverstreet@xxxxxxxxxx>> > > > > diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c > > index 5304eaa..48efd4d 100644 > > --- a/drivers/md/bcache/io.c > > +++ b/drivers/md/bcache/io.c > > @@ -163,13 +163,6 @@ static unsigned bch_bio_max_sectors(struct > bio *bio) > > struct bio_vec *bv, *end = bio_iovec(bio) + > > min_t(int, bio_segments(bio), max_segments); > > > > - struct bvec_merge_data bvm = { > > - .bi_bdev = bio->bi_bdev, > > - .bi_sector = bio->bi_sector, > > - .bi_size = 0, > > - .bi_rw = bio->bi_rw, > > - }; > > - > > if (bio->bi_rw & REQ_DISCARD) > > return min(ret, q->limits.max_discard_sectors); > > > > @@ -178,12 +171,18 @@ static unsigned bch_bio_max_sectors(struct > bio *bio) > > ret = 0; > > > > for (bv = bio_iovec(bio); bv < end; bv++) { > > + struct bvec_merge_data bvm = { > > + .bi_bdev = bio->bi_bdev, > > + .bi_sector = bio->bi_sector, > > + .bi_size = ret << 9, > > + .bi_rw = bio->bi_rw, > > + }; > > + > > if (q->merge_bvec_fn && > > q->merge_bvec_fn(q, &bvm, bv) < (int) > bv->bv_len) > > break; > > > > - ret += bv->bv_len >> 9; > > - bvm.bi_size += bv->bv_len; > > + ret += bv->bv_len >> 9; > > } > > } > > > > > > > > > -- > > Mit freundlichen Grüßen, > Best Regards, > > Jack Wang > > Linux Kernel Developer Storage > ProfitBricks GmbH The IaaS-Company. > > Beschreibung: Beschreibung: Beschreibung: > cid:part1.00030702.00050402@profitbricks.com > > *ProfitBricks GmbH* > Greifswalder Str. 207 > D - 10405 Berlin > Tel: +49 30 6098 56991-308 > Fax: +49 30 6098 56992-203 > Email: jinpu.wang@xxxxxxxxxxxxxxxx <http://profitbricks.com> > URL: http://www.profitbricks.com <http://www.profitbricks.com/> > > Sitz der Gesellschaft: Berlin. > Registergericht: Amtsgericht Charlottenburg, HRB 125506 B. > Geschäftsführer: Andreas Gauger, Achim Weiss. -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
