From: Christoph Hellwig <hch@lst.de>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Christoph Hellwig <hch@lst.de>,
clm@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2] btrfs: don't limit direct reads to a single sector
Date: Tue, 21 Jun 2022 08:40:10 +0200 [thread overview]
Message-ID: <20220621064010.GA893@lst.de> (raw)
In-Reply-To: <221407c5-0aec-6ab0-4f7f-e74a5873e4e0@gmx.com>
On Tue, Jun 21, 2022 at 02:35:55PM +0800, Qu Wenruo wrote:
> In fact, one bio vector can point to multiple pages, as its bv_len can
> be larger than PAGE_SIZE.
Yes, it can. But it usually doesn't, as that requires contigous memory.
Without the large folio support now merges for xfs/iomap that is very
unusual and tends to happen only soon after booting. At which point
allocating the larger csums array is also not a problem as we can
find contigous memory for that easily as well. For direct I/O on the
other hand the destination could be THPs or hugetlbs even when memory
is badly fragmented.
next prev parent reply other threads:[~2022-06-21 6:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-21 6:26 [PATCH v2] btrfs: don't limit direct reads to a single sector Christoph Hellwig
2022-06-21 6:35 ` Qu Wenruo
2022-06-21 6:40 ` Christoph Hellwig [this message]
2022-06-21 6:55 ` Qu Wenruo
2022-06-21 6:59 ` Christoph Hellwig
2022-06-21 7:04 ` Qu Wenruo
2022-06-21 8:37 ` Nikolay Borisov
2022-06-21 13:34 ` David Sterba
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