From: Jens Axboe <axboe@kernel.dk>
To: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Cc: io-uring@vger.kernel.org
Subject: Re: [RFC 1/2] io_uring: don't use kiocb.private to store buf_index
Date: Tue, 19 May 2020 16:20:57 -0600 [thread overview]
Message-ID: <91cd9cdb-b65a-879c-0318-a888d2658bed@kernel.dk> (raw)
In-Reply-To: <6ce9f56d-d4eb-0db1-6ea3-166aed29807f@kernel.dk>
On 5/19/20 4:07 PM, Jens Axboe wrote:
> On 5/19/20 3:52 PM, Bijan Mottahedeh wrote:
>> kiocb.private is used in iomap_dio_rw() so store buf_index separately.
>
> Hmm, that's no good, the owner of the iocb really should own ->private
> as well.
>
> The downside of this patch is that io_rw now spills into the next
> cacheline, which propagates to io_kiocb as well. iocb has 4 bytes
> of padding, but probably cleaner if we can stuff it into io_kiocb
> instead. How about adding a u16 after opcode? There's a 2 byte
> hole there, so it would not impact the size of io_kiocb.
I applied your patch, but moved the buf_index to not grow the
structure:
https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.7&id=4f4eeba87cc731b200bff9372d14a80f5996b277
--
Jens Axboe
next prev parent reply other threads:[~2020-05-19 22:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 21:52 [RFC 0/2] io_uring: don't use kiocb.private to store buf_index Bijan Mottahedeh
2020-05-19 21:52 ` [RFC 1/2] " Bijan Mottahedeh
2020-05-19 22:07 ` Jens Axboe
2020-05-19 22:20 ` Jens Axboe [this message]
2020-05-19 22:48 ` Bijan Mottahedeh
2020-05-19 21:52 ` [RFC 2/2] io_uring: mark REQ_NOWAIT for a non-mq queue as unspported Bijan Mottahedeh
2020-05-19 22:16 ` Fwd: " Jens Axboe
2020-05-20 17:50 ` Christoph Hellwig
2020-05-28 18:35 ` Jeff Moyer
2020-05-28 19:01 ` Jens Axboe
2020-05-28 19:22 ` Jens Axboe
2020-05-28 19:31 ` Jeff Moyer
2020-05-28 22:12 ` Jeff Moyer
2020-05-28 23:03 ` Jens Axboe
2020-05-29 15:02 ` Jeff Moyer
2020-05-29 16:20 ` Jens Axboe
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