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Groups > linux.kernel > #1227166
| From | Jens Axboe <axboe@kernel.dk> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios |
| Date | 2015-09-17 18:10 +0200 |
| Message-ID | <q9JV0-bo-11@gated-at.bofh.it> (permalink) |
| References | <q9J8C-7rl-23@gated-at.bofh.it> <q9J8C-7rl-21@gated-at.bofh.it> <q9JLk-8c4-13@gated-at.bofh.it> <q9JLk-8c4-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 09/17/2015 09:55 AM, Jens Axboe wrote: > On 09/17/2015 09:50 AM, Ming Lei wrote: >> On Thu, Sep 17, 2015 at 11:19 PM, Jens Axboe <axboe@kernel.dk> wrote: >>> On 09/17/2015 09:13 AM, Ming Lei wrote: >>>> >>>> biovecs has become immutable since v3.13, so it isn't necessary >>>> to allocate biovecs for the new cloned bios, then we can save >>>> one extra biovecs allocation/copy, and the allocation is often >>>> not fixed-length and a bit more expensive. >>>> >>>> For example, if the 'max_sectors_kb' of null blk's queue is set >>>> as 16(32 sectors) via sysfs just for making more splits, this patch >>>> can increase throught about ~70% in the sequential read test over >>>> null_blk(direct io, bs: 1M). >>> >>> >>> I'd be curious how this compares to before we did the splitting, not >>> exceeding the limits through bio_add_page() instead? >> >> Let me show these test results: >> >> ---------------------------------------------------------------------------------- >> >> kernel | throught >> ---------------------------------------------------------------------------------- >> >> 4.3.0-rc1-next-20150916 | bw=12227MB/s, iops=12227 >> ---------------------------------------------------------------------------------- >> >> 4.3.0-rc1-next-20150916 with patch | bw=21011MB/s, iops=21011 >> ---------------------------------------------------------------------------------- >> >> v4.2 | >> bw=18959MB/s, iops=18958 >> ---------------------------------------------------------------------------------- >> >> >> So from the above, looks this patch is kind of fix for performance >> regression >> introduced by 54efd50bfd(block: make generic_make_request handle >> arbitrarily sized bios), :-) > > So that's 1MB user IO, and 16KB device limit, correct? If that is the > case, then the results make sense. And looks like we're still ahead of > the older bio_add_page() approach, which is what I mostly cared about. > Thanks! I'll apply this for -rc2. Hand applied, as it didn't apply with the blk-merge.c warning fix at all (against for-linus). Please double check: http://git.kernel.dk/cgit/linux-block/commit/?h=for-linus&id=52cc6eead9095e2faf2ec7afc013aa3af1f01ac5 -- Jens Axboe -- 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/
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Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios Jens Axboe <axboe@kernel.dk> - 2015-09-17 17:20 +0200
Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios Jens Axboe <axboe@kernel.dk> - 2015-09-17 18:00 +0200
Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios Jens Axboe <axboe@kernel.dk> - 2015-09-17 18:10 +0200
Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios Ming Lei <ming.lei@canonical.com> - 2015-09-17 18:10 +0200
Re: [PATCH] block: blk-merge: fast-clone bio when splitting rw bios Ming Lei <ming.lei@canonical.com> - 2015-09-17 18:00 +0200
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