Re: [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls

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From: Johannes Weiner <hannes@cmpxchg.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
	Matthew Wilcox <willy@infradead.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	David Sterba <dsterba@suse.com>, Gao Xiang <xiang@kernel.org>,
	Chao Yu <chao@kernel.org>,
	linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls
Date: Wed, 14 Sep 2022 12:41:40 +0100	[thread overview]
Message-ID: <YyG99D196Hj0/GgZ@cmpxchg.org> (raw)
In-Reply-To: <20220910065058.3303831-2-hch@lst.de>

On Sat, Sep 10, 2022 at 08:50:54AM +0200, Christoph Hellwig wrote:
> PSI tries to account for the cost of bringing back in pages discarded by
> the MM LRU management.  Currently the prime place for that is hooked into
> the bio submission path, which is a rather bad place:
> 
>  - it does not actually account I/O for non-block file systems, of which
>    we have many
>  - it adds overhead and a layering violation to the block layer
> 
> Add the accounting into the two places in the core MM code that read
> pages into an address space by calling into ->read_folio and ->readahead
> so that the entire file system operations are covered, to broaden
> the coverage and allow removing the accounting in the block layer going
> forward.
> 
> As psi_memstall_enter can deal with nested calls this will not lead to
> double accounting even while the bio annotations are still present.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

This is much cleaner. With the fixlet Willy pointed out:

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

WARNING: multiple messages have this Message-ID (diff)

From: Johannes Weiner <hannes@cmpxchg.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-mm@kvack.org, linux-erofs@lists.ozlabs.org,
	Josef Bacik <josef@toxicpanda.com>,
	Matthew Wilcox <willy@infradead.org>,
	linux-block@vger.kernel.org, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.com>,
	linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Suren Baghdasaryan <surenb@google.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls
Date: Wed, 14 Sep 2022 12:41:40 +0100	[thread overview]
Message-ID: <YyG99D196Hj0/GgZ@cmpxchg.org> (raw)
In-Reply-To: <20220910065058.3303831-2-hch@lst.de>

On Sat, Sep 10, 2022 at 08:50:54AM +0200, Christoph Hellwig wrote:
> PSI tries to account for the cost of bringing back in pages discarded by
> the MM LRU management.  Currently the prime place for that is hooked into
> the bio submission path, which is a rather bad place:
> 
>  - it does not actually account I/O for non-block file systems, of which
>    we have many
>  - it adds overhead and a layering violation to the block layer
> 
> Add the accounting into the two places in the core MM code that read
> pages into an address space by calling into ->read_folio and ->readahead
> so that the entire file system operations are covered, to broaden
> the coverage and allow removing the accounting in the block layer going
> forward.
> 
> As psi_memstall_enter can deal with nested calls this will not lead to
> double accounting even while the bio annotations are still present.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

This is much cleaner. With the fixlet Willy pointed out:

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

next prev parent reply	other threads:[~2022-09-14 11:41 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-10  6:50 improve pagecache PSI annotations Christoph Hellwig
2022-09-10  6:50 ` Christoph Hellwig
2022-09-10  6:50 ` [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls Christoph Hellwig
2022-09-10  6:50   ` Christoph Hellwig
2022-09-10 11:34   ` Jens Axboe
2022-09-10 11:34     ` Jens Axboe
2022-09-12  8:35     ` Christoph Hellwig
2022-09-12  8:35       ` Christoph Hellwig
2022-09-10 18:26   ` Matthew Wilcox
2022-09-10 18:26     ` Matthew Wilcox
2022-09-12  8:33     ` Christoph Hellwig
2022-09-12  8:33       ` Christoph Hellwig
2022-09-14 11:41   ` Johannes Weiner [this message]
2022-09-14 11:41     ` Johannes Weiner
2022-09-10  6:50 ` [PATCH 2/5] sched/psi: export psi_memstall_{enter,leave} Christoph Hellwig
2022-09-10  6:50   ` Christoph Hellwig
2022-09-14 11:42   ` Johannes Weiner
2022-09-14 11:42     ` Johannes Weiner
2022-09-10  6:50 ` [PATCH 3/5] btrfs: add manual PSI accounting for compressed reads Christoph Hellwig
2022-09-10  6:50   ` Christoph Hellwig
2022-09-12 15:28   ` David Sterba
2022-09-12 15:28     ` David Sterba
2022-09-14 11:46   ` Johannes Weiner
2022-09-14 11:46     ` Johannes Weiner
2022-09-10  6:50 ` [PATCH 4/5] erofs: add manual PSI accounting for the compressed address space Christoph Hellwig
2022-09-10  6:50   ` Christoph Hellwig
2022-09-14 11:47   ` Johannes Weiner
2022-09-14 11:47     ` Johannes Weiner
2022-09-14 12:47   ` Gao Xiang
2022-09-14 12:47     ` Gao Xiang
2022-09-10  6:50 ` [PATCH 5/5] block: remove PSI accounting from the bio layer Christoph Hellwig
2022-09-10  6:50   ` Christoph Hellwig
2022-09-14 11:48   ` Johannes Weiner
2022-09-14 11:48     ` Johannes Weiner
2022-09-10 11:32 ` improve pagecache PSI annotations Jens Axboe
2022-09-10 11:32   ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2022-09-15  9:41 improve pagecache PSI annotations v2 Christoph Hellwig
2022-09-15  9:41 ` [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls Christoph Hellwig
2022-09-15  9:41   ` Christoph Hellwig

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