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From: Ming Lei <[email protected]>
To: Pavel Begunkov <[email protected]>
Cc: [email protected], Jens Axboe <[email protected]>,
	Christoph Hellwig <[email protected]>,
	Matthew Wilcox <[email protected]>,
	Johannes Weiner <[email protected]>,
	Alexander Viro <[email protected]>,
	"Darrick J . Wong" <[email protected]>,
	"Martin K . Petersen" <[email protected]>,
	Jonathan Corbet <[email protected]>,
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], Christoph Hellwig <[email protected]>
Subject: Re: [PATCH v3 3/7] block/psi: remove PSI annotations from direct IO
Date: Mon, 11 Jan 2021 10:52:05 +0800	[thread overview]
Message-ID: <20210111025205.GD4147870@T590> (raw)
In-Reply-To: <faad7d7f58ff45285eaac9af7fae9a5fcca98977.1610170479.git.asml.silence@gmail.com>

On Sat, Jan 09, 2021 at 04:02:59PM +0000, Pavel Begunkov wrote:
> Direct IO does not operate on the current working set of pages managed
> by the kernel, so it should not be accounted as memory stall to PSI
> infrastructure.
> 
> The block layer and iomap direct IO use bio_iov_iter_get_pages()
> to build bios, and they are the only users of it, so to avoid PSI
> tracking for them clear out BIO_WORKINGSET flag. Do same for
> dio_bio_submit() because fs/direct_io constructs bios by hand directly
> calling bio_add_page().
> 
> Reported-by: Christoph Hellwig <[email protected]>
> Suggested-by: Christoph Hellwig <[email protected]>
> Suggested-by: Johannes Weiner <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
>  block/bio.c    | 6 ++++++
>  fs/direct-io.c | 2 ++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 1f2cc1fbe283..9f26984af643 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -1099,6 +1099,9 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
>   * fit into the bio, or are requested in @iter, whatever is smaller. If
>   * MM encounters an error pinning the requested pages, it stops. Error
>   * is returned only if 0 pages could be pinned.
> + *
> + * It's intended for direct IO, so doesn't do PSI tracking, the caller is
> + * responsible for setting BIO_WORKINGSET if necessary.
>   */
>  int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
>  {
> @@ -1123,6 +1126,9 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
>  
>  	if (is_bvec)
>  		bio_set_flag(bio, BIO_NO_PAGE_REF);
> +
> +	/* don't account direct I/O as memory stall */
> +	bio_clear_flag(bio, BIO_WORKINGSET);
>  	return bio->bi_vcnt ? 0 : ret;
>  }
>  EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index d53fa92a1ab6..0e689233f2c7 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -426,6 +426,8 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
>  	unsigned long flags;
>  
>  	bio->bi_private = dio;
> +	/* don't account direct I/O as memory stall */
> +	bio_clear_flag(bio, BIO_WORKINGSET);
>  
>  	spin_lock_irqsave(&dio->bio_lock, flags);
>  	dio->refcount++;
> -- 
> 2.24.0
> 

Reviewed-by: Ming Lei <[email protected]>

-- 
Ming


  reply	other threads:[~2021-01-11  2:53 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-09 16:02 [PATCH v3 0/7] no-copy bvec Pavel Begunkov
2021-01-09 16:02 ` [PATCH v3 1/7] splice: don't generate zero-len segement bvecs Pavel Begunkov
2021-01-11  2:48   ` Ming Lei
2021-01-09 16:02 ` [PATCH v3 2/7] bvec/iter: disallow zero-length segment bvecs Pavel Begunkov
2021-01-11  2:49   ` Ming Lei
2021-01-09 16:02 ` [PATCH v3 3/7] block/psi: remove PSI annotations from direct IO Pavel Begunkov
2021-01-11  2:52   ` Ming Lei [this message]
2021-01-09 16:03 ` [PATCH v3 4/7] target/file: allocate the bvec array as part of struct target_core_file_cmd Pavel Begunkov
2021-01-11  2:53   ` Ming Lei
2021-01-09 16:03 ` [PATCH v3 5/7] iov_iter: optimise bvec iov_iter_advance() Pavel Begunkov
2021-01-11  2:55   ` Ming Lei
2021-01-09 16:03 ` [PATCH v3 6/7] bio: add a helper calculating nr segments to alloc Pavel Begunkov
2021-01-11  2:57   ` Ming Lei
2021-01-09 16:03 ` [PATCH v3 7/7] bio: don't copy bvec for direct IO Pavel Begunkov
2021-01-11  3:00   ` Ming Lei
2021-01-25 15:58 ` [PATCH v3 0/7] no-copy bvec Jens Axboe

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