* [PATCH 1/2] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices.
@ 2012-07-16 1:30 majianpeng
2012-07-16 5:21 ` NeilBrown
0 siblings, 1 reply; 3+ messages in thread
From: majianpeng @ 2012-07-16 1:30 UTC (permalink / raw)
To: Neil Brown, viro; +Cc: linux-raid, linux-fsdevel
For regular file, write operaion used blk_plug function.But for block
file,write operation did not use blk_plug.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
---
fs/block_dev.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c2bbe1f..22cd436 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -215,9 +215,14 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
+ struct blk_plug plug;
+ ssize_t ret;
- return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
+ blk_start_plug(&plug);
+ ret = __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
nr_segs, blkdev_get_blocks, NULL, NULL, 0);
+ blk_finish_plug(&plug);
+ return ret;
}
int __sync_blockdev(struct block_device *bdev, int wait)
--
1.7.5.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/2] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices.
2012-07-16 1:30 [PATCH 1/2] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices majianpeng
@ 2012-07-16 5:21 ` NeilBrown
2012-07-16 5:30 ` majianpeng
0 siblings, 1 reply; 3+ messages in thread
From: NeilBrown @ 2012-07-16 5:21 UTC (permalink / raw)
To: majianpeng; +Cc: viro, linux-raid, linux-fsdevel, axboe
[-- Attachment #1: Type: text/plain, Size: 1973 bytes --]
On Mon, 16 Jul 2012 09:30:50 +0800 majianpeng <majianpeng@gmail.com> wrote:
> For regular file, write operaion used blk_plug function.But for block
> file,write operation did not use blk_plug.
>
> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
> ---
> fs/block_dev.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c2bbe1f..22cd436 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -215,9 +215,14 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
> {
> struct file *file = iocb->ki_filp;
> struct inode *inode = file->f_mapping->host;
> + struct blk_plug plug;
> + ssize_t ret;
>
> - return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
> + blk_start_plug(&plug);
> + ret = __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
> nr_segs, blkdev_get_blocks, NULL, NULL, 0);
> + blk_finish_plug(&plug);
> + return ret;
> }
>
> int __sync_blockdev(struct block_device *bdev, int wait)
[cc:ing Jens Axboe]
I think we do need something like this, but I don't think this is the right
place for it.
For normal filesystem writes, the blk_{start,finish}_plug calls are in
generic_file_aio_write which is the "aio_write" function, or is called by it.
aio_write calls generic_file_aio_write, calls blk_start_plug, call
__generic_file_aio_write.
For block devices we bypass the generic_file_aio_write:
aio_write calls blkdev_aio_write calls __generic_file_aio_write - without
calling blk_start_plug.
So I think the calls to blk_start_plug and blk_finish_plug should go in
blkdev_aio_write. i.e. blkdev_aio_write should be made to look more like
generic_file_aio_write (just without the mutex_lock/unlock).
If you redo the patch like that and test it I'll happily add my Reviewed-by.
I suspect it should be merged through Jens' tree.
Thanks,
NeilBrown
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Re: [PATCH 1/2] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices.
2012-07-16 5:21 ` NeilBrown
@ 2012-07-16 5:30 ` majianpeng
0 siblings, 0 replies; 3+ messages in thread
From: majianpeng @ 2012-07-16 5:30 UTC (permalink / raw)
To: Neil Brown; +Cc: viro, linux-raid, linux-fsdevel, axboe
On 2012-07-16 13:21 NeilBrown <neilb@suse.de> Wrote:
>On Mon, 16 Jul 2012 09:30:50 +0800 majianpeng <majianpeng@gmail.com> wrote:
>
>> For regular file, write operaion used blk_plug function.But for block
>> file,write operation did not use blk_plug.
>>
>> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
>> ---
>> fs/block_dev.c | 7 ++++++-
>> 1 files changed, 6 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index c2bbe1f..22cd436 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -215,9 +215,14 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
>> {
>> struct file *file = iocb->ki_filp;
>> struct inode *inode = file->f_mapping->host;
>> + struct blk_plug plug;
>> + ssize_t ret;
>>
>> - return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
>> + blk_start_plug(&plug);
>> + ret = __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
>> nr_segs, blkdev_get_blocks, NULL, NULL, 0);
>> + blk_finish_plug(&plug);
>> + return ret;
>> }
>>
>> int __sync_blockdev(struct block_device *bdev, int wait)
>
>[cc:ing Jens Axboe]
>
>I think we do need something like this, but I don't think this is the right
>place for it.
>
>For normal filesystem writes, the blk_{start,finish}_plug calls are in
>generic_file_aio_write which is the "aio_write" function, or is called by it.
>aio_write calls generic_file_aio_write, calls blk_start_plug, call
>__generic_file_aio_write.
>
>For block devices we bypass the generic_file_aio_write:
>
>aio_write calls blkdev_aio_write calls __generic_file_aio_write - without
>calling blk_start_plug.
>So I think the calls to blk_start_plug and blk_finish_plug should go in
>blkdev_aio_write. i.e. blkdev_aio_write should be made to look more like
>generic_file_aio_write (just without the mutex_lock/unlock).
>
>If you redo the patch like that and test it I'll happily add my Reviewed-by.
>
>I suspect it should be merged through Jens' tree.
>
>Thanks,
>NeilBrown
>
>
Thanks, i'll do it and resend the patch.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-07-16 1:30 [PATCH 1/2] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices majianpeng
2012-07-16 5:21 ` NeilBrown
2012-07-16 5:30 ` majianpeng
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