Messages in this thread | | | Date | Wed, 23 Jul 2014 12:05:26 +0800 | From | Gu Zheng <> | Subject | Re: [PATCH 4/4] aio: use iovec array rather than the single one |
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Hi Jeff, On 07/22/2014 11:20 PM, Jeff Moyer wrote:
> Gu Zheng <guz.fnst@cn.fujitsu.com> writes: > >> use an iovec array rather than the single one, so that we can avoid >> to alloc more iovecs buffer in small(< 8) PREADV/PWRITEV cases. > > I did some basic functional testing of this change and the change in > patch 1/4. That testing included using aio-stress to drive queue depths > of 7, 8 and 9, and verify that it didn't fall over. I also ran xfstests > './check -g aio', and libaio's 'make partcheck'.
> > The change looks good to me, and passed testing, so: > > Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Thanks for your review and test.
> > However, I still would like some comment on the reasoning behind it, and > whether there is some measurable performance advantage for some > workload. Additionally, it would be nice if that comment made its way > into the commit message.
I'll add more useful info, and send it out later.
Thanks, Gu
> > Cheers, > Jeff > >> >> 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 0cd0479..ef21efe 100644 >> --- a/fs/aio.c >> +++ b/fs/aio.c >> @@ -1260,12 +1260,12 @@ 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; >> >> @@ -1302,7 +1302,7 @@ 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) { >> @@ -1337,7 +1337,7 @@ 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; >> } >> @@ -1384,7 +1384,7 @@ rw_common: >> return -EINVAL; >> } >> >> - if (iovec != &inline_vec) >> + if (iovec != inline_vecs) >> kfree(iovec); >> >> if (ret != -EIOCBQUEUED) { > . >
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