From: David Sterba <dsterba@suse.cz>
To: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>,
Linux BTRFS Mailinglist <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH] btrfs: simplify read_extent_buffer_pages a bit
Date: Thu, 11 Apr 2019 18:59:35 +0200 [thread overview]
Message-ID: <20190411165935.GA3476@twin.jikos.cz> (raw)
In-Reply-To: <20190411164059.4981-1-jthumshirn@suse.de>
On Thu, Apr 11, 2019 at 06:40:59PM +0200, Johannes Thumshirn wrote:
> Currently read_extent_buffer_pages() uses a 4 pass algorithm to read an
> extent buffer's pages from disk, all 4 stages looping over all pages of
> the extent buffer.
>
> 1) Loop over all pages and lock them.
> 2) Loop over all pages and see if one is not marked as PageUptodate, so we
> can break out of the function early.
> 3) Loop over all pages and if the page is !PageUptodate read the page,
> otherwise unlock the page.
> 4) Loop over all pages and wait for stable pages.
>
> Unify the 1st two for loops, we can count the number of uptodate pages
> after we have locked them without the need for re-starting the loop.
Effectively reverting 2571e739677f1e4c0c63f5ed49adcc0857923625 that
fixed a bug. Please have a look if something has really changed so that
the split loops are no longer necessary.
next prev parent reply other threads:[~2019-04-11 16:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-11 16:40 [PATCH] btrfs: simplify read_extent_buffer_pages a bit Johannes Thumshirn
2019-04-11 16:59 ` David Sterba [this message]
2019-04-16 9:16 ` Johannes Thumshirn
2019-04-17 12:20 ` David Sterba
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