From: David Sterba <dsterba@suse.cz>
To: ira.weiny@intel.com
Cc: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/4] fs/btrfs: Convert raid5/6 kmaps to kmap_local_page()
Date: Fri, 12 Mar 2021 20:26:34 +0100 [thread overview]
Message-ID: <20210312192634.GS7604@suse.cz> (raw)
In-Reply-To: <20210217024826.3466046-3-ira.weiny@intel.com>
On Tue, Feb 16, 2021 at 06:48:24PM -0800, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> These kmaps are thread local and don't need to be atomic. So they can use
> the more efficient kmap_local_page(). However, the mapping of pages in
> the stripes and the additional parity and qstripe pages are a bit
> trickier because the unmapping must occur in the opposite order from the
> mapping. Furthermore, the pointer array in __raid_recover_end_io() may
> get reordered.
>
> Convert these calls to kmap_local_page() taking care to reverse the
> unmappings of any page arrays as well as being careful with the mappings
> of any special pages such as the parity and qstripe pages.
Though there's one more allocation for the additional array, I don't see
a simpler way to avoid it and track the array reordering at a lower
memory cost. At least it's not in a performance critical code and the
array size is reasonably small.
next prev parent reply other threads:[~2021-03-12 19:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 2:48 [PATCH 0/4] btrfs: Convert more kmaps to kmap_local_page() ira.weiny
2021-02-17 2:48 ` [PATCH 1/4] fs/btrfs: Convert kmap to kmap_local_page() using coccinelle ira.weiny
2021-03-12 18:58 ` David Sterba
2021-03-12 20:03 ` Ira Weiny
2021-03-16 11:04 ` David Sterba
2021-02-17 2:48 ` [PATCH 2/4] fs/btrfs: Convert raid5/6 kmaps to kmap_local_page() ira.weiny
2021-03-12 19:26 ` David Sterba [this message]
2021-02-17 2:48 ` [PATCH 3/4] fs/btrfs: Use kmap_local_page() in __btrfsic_submit_bio() ira.weiny
2021-02-17 2:48 ` [PATCH 4/4] fs/btrfs: Convert block context kmap's to kmap_local_page() ira.weiny
2021-03-11 21:30 ` [PATCH 0/4] btrfs: Convert more kmaps " Ira Weiny
2021-03-12 19:41 ` David Sterba
2021-03-12 20:05 ` Ira Weiny
2021-03-16 11:07 ` David Sterba
2021-03-16 16:56 ` Ira Weiny
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