Re: [PATCH RFC v2 1/2] filemap: defer dropbehind invalidation from IRQ context

Christoph Hellwig <[email protected]> Thu, 26 Feb 2026 14:04:09 -0800

Newsgroups	dev.linux.lists.ntfs3,org.kernel.vger.linux-block,org.kernel.vger.linux-ext4,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-nilfs,org.kvack.linux-mm
Message-ID	<[email protected]>

On Wed, Feb 25, 2026 at 03:52:41PM -0700, Jens Axboe wrote:
> One solution could potentially be to use per-cpu lists for this. If you
> have N threads working on separate block devices, they will tend to be
> sticky to their CPU anyway.

Having per-cpu lists would be nice, but I'd really love to have them
in iomap, as we have quite a few iomap features that would benefit
from generic offload to user context on completion.  Right now we
only have code for that in XFS, and that's because the list is anchored
in the inode.  Based on the commit message in cb357bf3d105f that's
intentional for the write completions there, but for all other
completions a generic per-cpu list would probably work fine.