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From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <wqu@suse.com>
Cc: Anand Jain <anand.jain@oracle.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 2/3] btrfs: small improvement for btrfs_io_context structure
Date: Thu, 2 Feb 2023 22:19:37 -0800	[thread overview]
Message-ID: <Y9yneQhuePjT/92P@infradead.org> (raw)
In-Reply-To: <61d2d841-778b-ca13-cc41-ca115b5ed287@suse.com>

On Thu, Feb 02, 2023 at 02:47:13PM +0800, Qu Wenruo wrote:
> Because the tgtdev_map would soon get completely removed in the next patch.
> 
> Just to mention, I don't like the current way to allocate memory at all.
> 
> If there is more feedback, I can convert the allocation to the same way as
> alloc_rbio() of raid56.c, AKA, use dedicated kcalloc() calls for those
> arrays.

The real elephant in the room is that the io_context needs to use a
mempool anyway to be deadlock safe.  Which means we'll need to size
for the worst case (per file system?) here.  Fortunately the read
fast path now doesn't use the io_context at all which helps with
the different sizing optimizations.

  parent reply	other threads:[~2023-02-03  6:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-28  8:23 [PATCH 0/3] btrfs: reduce the memory usage for replace in btrfs_io_context Qu Wenruo
2023-01-28  8:23 ` [PATCH 1/3] btrfs: simplify the @bioc argument for handle_ops_on_dev_replace() Qu Wenruo
2023-01-30  7:17   ` Johannes Thumshirn
2023-01-31 11:54   ` Anand Jain
2023-01-28  8:23 ` [PATCH 2/3] btrfs: small improvement for btrfs_io_context structure Qu Wenruo
2023-01-30  7:27   ` Johannes Thumshirn
2023-01-30  7:31     ` Qu Wenruo
2023-02-02  6:28   ` Anand Jain
2023-02-02  6:47     ` Qu Wenruo
2023-02-02  9:12       ` Anand Jain
2023-02-07  2:19         ` Qu Wenruo
2023-02-03  6:19       ` Christoph Hellwig [this message]
2023-02-03  6:44         ` Qu Wenruo
2023-01-28  8:23 ` [PATCH 3/3] btrfs: use a more space efficient way to represent the source of duplicated stripes Qu Wenruo
2023-01-30  7:40   ` Johannes Thumshirn

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