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From:   Gi-Oh Kim <gi-oh.kim@profitbricks.com>
Date:   Thu, 21 Jun 2018 10:40:37 +0200
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Subject: Re: [PATCH V6 00/30] block: support multipage bvec
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@fb.com>, hch@infradead.org,
        Al Viro <viro@zeniv.linux.org.uk>,
        Kent Overstreet <kent.overstreet@gmail.com>, dsterba@suse.cz,
        ying.huang@intel.com, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, "Theodore Ts'o" <tytso@mit.edu>,
        darrick.wong@oracle.com, colyli@suse.de,
        Filipe Manana <fdmanana@gmail.com>, rdunlap@infradead.org
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On Thu, Jun 21, 2018 at 3:17 AM, Ming Lei <ming.lei@redhat.com> wrote:
> On Fri, Jun 15, 2018 at 02:59:19PM +0200, Gi-Oh Kim wrote:
>> >
>> > - bio size can be increased and it should improve some high-bandwidth =
IO
>> > case in theory[4].
>> >
>>
>> Hi,
>>
>> I would like to report your patch set works well on my system based on v=
4.14.48.
>> I thought the multipage bvec could improve the performance of my system.
>> (FYI, my system has v4.14.48 and provides KVM-base virtualization servic=
e.)
>
> Thanks for your test!
>
>>
>> So I did back-porting your patches to v4.14.48.
>> It has done without any serious problem.
>> I only needed to cherry-pick "blk-merge: compute
>> bio->bi_seg_front_size efficiently" and
>> "block: move bio_alloc_pages() to bcache" patches before back-porting
>> to prevent conflicts.
>
> Not sure I understand your point, you have to backport all patches.

Never mind.
I just meant I did backporting for myself and it is still working well.

>
> At least now, BIO_MAX_PAGES can be fixed as 256 in case of CONFIG_THP_SWA=
P,
> otherwise 2 pages may be allocated for holding the bvec table, so tests
> in case of THP_SWAP may be improved.
>
> Also filesystem may support IO to/from THP, and multipage bvec should
> improve this case too.

OK, I got it.
I will find something to use THP_SWAP and run the performance test with it.
Thank you ;-)


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