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Date: Mon, 5 May 2025 07:57:56 +0200
From: hch <hch@lst.de>
To: Hans Holmberg <Hans.Holmberg@wdc.com>
Cc: "linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
	Carlos Maiolino <cem@kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	"Darrick J . Wong" <djwong@kernel.org>, hch <hch@lst.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/2] Add mru cache for inode to zone allocation
 mapping
Message-ID: <20250505055756.GB21256@lst.de>
References: <20250430084117.9850-1-hans.holmberg@wdc.com>
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On Wed, Apr 30, 2025 at 08:41:20AM +0000, Hans Holmberg wrote:
> Sending out as an RFC to get comments, specifically about the potential
> mru lock contention when doing the lookup during allocation.

I am a little worried about that.  The MRU cache is implemented right
now rotates the mru list on every lookup under a mru-cache wide lock,
which is bit of a performance nightmare.

I wonder if we can do some form of batched move between the mru buckets
that can reduce the locking and cacheline write impact.

But maybe it's worth to give this a try and work from performance reports
as needed.