From: Jeff Moyer <jmoyer@redhat.com>
To: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: bcrl@kvack.org, axboe@kernel.dk, akpm@linux-foundation.org,
linux-aio@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH 4/4] aio: use iovec array rather than the single one
Date: Wed, 23 Jul 2014 09:25:57 -0400 [thread overview]
Message-ID: <x497g34w6je.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <1406109834-4414-4-git-send-email-guz.fnst@cn.fujitsu.com> (Gu Zheng's message of "Wed, 23 Jul 2014 18:03:54 +0800")
Gu Zheng <guz.fnst@cn.fujitsu.com> writes:
> Previously, we only offer a single iovec to handle all the read/write cases, so
> the PREADV/PWRITEV request always need to alloc more iovec buffer when copying
> user vectors.
> If we use a tmp iovec array rather than the single one, some small PREADV/PWRITEV
> workloads(vector size small than the tmp buffer) will not need to alloc more
> iovec buffer when copying user vectors.
Hi, Gu,
This still doesn't explain why you decided to look into this. Did you
notice a performance issue in this path? Do you have benchmarks that
show some speedup due to this change?
Thanks,
Jeff
>
> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> ---
> fs/aio.c | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index f1fede2..df3491a 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1267,12 +1267,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
> if (compat)
> ret = compat_rw_copy_check_uvector(rw,
> (struct compat_iovec __user *)buf,
> - *nr_segs, 1, *iovec, iovec);
> + *nr_segs, UIO_FASTIOV, *iovec, iovec);
> else
> #endif
> ret = rw_copy_check_uvector(rw,
> (struct iovec __user *)buf,
> - *nr_segs, 1, *iovec, iovec);
> + *nr_segs, UIO_FASTIOV, *iovec, iovec);
> if (ret < 0)
> return ret;
>
> @@ -1309,7 +1309,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
> fmode_t mode;
> aio_rw_op *rw_op;
> rw_iter_op *iter_op;
> - struct iovec inline_vec, *iovec = &inline_vec;
> + struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
> struct iov_iter iter;
>
> switch (opcode) {
> @@ -1344,7 +1344,7 @@ rw_common:
> if (!ret)
> ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
> if (ret < 0) {
> - if (iovec != &inline_vec)
> + if (iovec != inline_vecs)
> kfree(iovec);
> return ret;
> }
> @@ -1391,7 +1391,7 @@ rw_common:
> return -EINVAL;
> }
>
> - if (iovec != &inline_vec)
> + if (iovec != inline_vecs)
> kfree(iovec);
>
> if (ret != -EIOCBQUEUED) {
next parent reply other threads:[~2014-07-23 13:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1406109834-4414-1-git-send-email-guz.fnst@cn.fujitsu.com>
[not found] ` <1406109834-4414-4-git-send-email-guz.fnst@cn.fujitsu.com>
2014-07-23 13:25 ` Jeff Moyer [this message]
2014-07-24 1:15 ` [RESEND PATCH 4/4] aio: use iovec array rather than the single one Gu Zheng
2014-07-24 15:56 ` Benjamin LaHaise
2014-07-24 15:55 ` [RESEND PATCH 1/4] aio: remove the needless registration of ring file's private_data Benjamin LaHaise
[not found] ` <1406109834-4414-2-git-send-email-guz.fnst@cn.fujitsu.com>
2014-07-24 15:55 ` [RESEND PATCH 2/4] aio: use the macro rather than the inline magic number Benjamin LaHaise
[not found] ` <1406109834-4414-3-git-send-email-guz.fnst@cn.fujitsu.com>
2014-07-24 15:56 ` [RESEND PATCH 3/4] aio: fix some comments Benjamin LaHaise
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