From: Christoph Hellwig <hch@lst.de>
To: Kundan Kumar <kundan.kumar@samsung.com>
Cc: ritesh.list@gmail.com, vishak.g@samsung.com, jack@suse.cz,
"Darrick J. Wong" <djwong@kernel.org>,
amir73il@gmail.com, Dave Chinner <david@fromorbit.com>,
gfs2@lists.linux.dev, linux-mm@kvack.org, clm@meta.com,
Christoph Hellwig <hch@lst.de>,
dave@stgolabs.net, agruenba@redhat.com, miklos@szeredi.hu,
gost.dev@samsung.com, willy@infradead.org, anuj20.g@samsung.com,
linux-nfs@vger.kernel.org, viro@zeniv.linux.org.uk,
jaegeuk@kernel.org, axboe@kernel.dk, brauner@kernel.org,
linux-f2fs-devel@lists.sourceforge.net, mcgrof@kernel.org,
anna@kernel.org, linux-fsdevel@vger.kernel.org,
akpm@linux-foundation.org, trondmy@kernel.org
Subject: Re: [f2fs-dev] [PATCH v2 00/16] Parallelizing filesystem writeback
Date: Fri, 7 Nov 2025 14:37:42 +0100 [thread overview]
Message-ID: <20251107133742.GA5596@lst.de> (raw)
In-Reply-To: <91367b76-e48b-46b4-b10b-43dfdd8472fa@samsung.com>
On Fri, Nov 07, 2025 at 02:54:42PM +0530, Kundan Kumar wrote:
> Predicting the Allocation Group (AG) for aged filesystems and passing
> this information to per-AG writeback threads appears to be a complex
> task.
Yes. But in the end aged file systems are what will see most usage.
Fresh file systems look nice in benchmarks, but they aren't what
users will mostly deal with.
> To segregate these I/O requests by AG, it is necessary to associate
> AG-specific information with the pages/folios in the page cache. Two
> possible approaches are:
> (1) storing AG information in the folio->private field, or
> (2) introducing new markers in the xarray to track AG-specific data.
>
> The AG-affined writeback thread processes specific pages from the page
> cache marked for its AG. Is this a viable approach, or are there
> alternative solutions that could be more effective?
Or maybe the per-AG scheme isn't that great after all and we just
need some other simple sharding scheme? Of course lock contention
will be nicer on a per-AG basis, but as you found out actually
mapping high-level writeback to AGs is pretty hard.
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prev parent reply other threads:[~2025-11-07 13:37 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20251014120958epcas5p267c3c9f9dbe6ffc53c25755327de89f9@epcas5p2.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 00/16] Parallelizing filesystem writeback Kundan Kumar
[not found] ` <CGME20251014121014epcas5p11d254fd09fcc157ea69c39bd9c5984ed@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 01/16] writeback: add infra for parallel writeback Kundan Kumar
2025-10-21 11:52 ` Jan Kara
[not found] ` <CGME20251014121020epcas5p36ca8a0d6d74f7b81996bb367329feb4a@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 02/16] writeback: add support to initialize and free multiple writeback ctxs Kundan Kumar
[not found] ` <CGME20251014121026epcas5p1aecefead887a6b4b6745cca0519d1092@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 03/16] writeback: link bdi_writeback to its corresponding bdi_writeback_ctx Kundan Kumar
[not found] ` <CGME20251014121031epcas5p37b0c4e23a7ad2d623ba776498f795fb0@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 04/16] writeback: affine inode to a writeback ctx within a bdi Kundan Kumar
2025-10-21 11:58 ` Jan Kara
[not found] ` <CGME20251014121036epcas5p17c607955db032d076daa2e5cfecfe8ea@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 05/16] writeback: modify bdi_writeback search logic to search across all wb ctxs Kundan Kumar
2025-10-21 12:05 ` Jan Kara
[not found] ` <CGME20251014121042epcas5p16a955879f8aaca4d0a4fd50bc5344f55@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 06/16] writeback: invoke all writeback contexts for flusher and dirtytime writeback Kundan Kumar
[not found] ` <CGME20251014121048epcas5p4e8665c2e4e12367465aa4d4ec1de84d9@epcas5p4.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 07/16] writeback: modify sync related functions to iterate over all writeback contexts Kundan Kumar
[not found] ` <CGME20251014121056epcas5p1cd2a7fde9f54633b5a331f4553f88735@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 08/16] writeback: add support to collect stats for all writeback ctxs Kundan Kumar
[not found] ` <CGME20251014121102epcas5p3280cd3e6bf16a2fb6a7fe483751f07a7@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 09/16] f2fs: add support in f2fs to handle multiple writeback contexts Kundan Kumar
2025-10-15 7:29 ` Christoph Hellwig
[not found] ` <CGME20251014121108epcas5p1d68e41bdb1d51ae137b9bb22a7d16fd1@epcas5p1.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 10/16] fuse: add support for multiple writeback contexts in fuse Kundan Kumar
[not found] ` <CGME20251014121113epcas5p3522dd553825deccfb9a1c9c12f071e3a@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 11/16] gfs2: add support in gfs2 to handle multiple writeback contexts Kundan Kumar
[not found] ` <CGME20251014121117epcas5p3f095fc3e8c279700c7256e07cd780c5f@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 12/16] nfs: add support in nfs " Kundan Kumar
[not found] ` <CGME20251014121122epcas5p3a01a79d090c3cca8caaf78c0f411e4c4@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 13/16] writeback: configure the num of writeback contexts between 0 and number of online cpus Kundan Kumar
[not found] ` <CGME20251014121126epcas5p2ff20c9139bdd702c77b9de50e4f259c7@epcas5p2.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 14/16] writeback: segregated allocation and free of writeback contexts Kundan Kumar
[not found] ` <CGME20251014121130epcas5p3b76f1a7ab53a57403275e9ba5d3549a3@epcas5p3.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 15/16] writeback: added support to change the number of writebacks using a sysfs attribute Kundan Kumar
[not found] ` <CGME20251014121135epcas5p2aa801677c0561db10291c51d669873e2@epcas5p2.samsung.com>
2025-10-14 12:08 ` [f2fs-dev] [PATCH v2 16/16] writeback: added XFS support for matching writeback count to allocation group count Kundan Kumar
2025-10-15 7:30 ` Christoph Hellwig
2025-10-15 1:03 ` [f2fs-dev] [PATCH v2 00/16] Parallelizing filesystem writeback Andrew Morton
2025-10-15 8:54 ` Kundan Kumar
2025-10-15 7:31 ` Christoph Hellwig
2025-10-20 22:46 ` Dave Chinner via Linux-f2fs-devel
2025-10-21 10:36 ` Kundan Kumar
2025-10-21 12:11 ` Jan Kara
2025-10-23 11:41 ` Kundan Kumar
2025-10-22 4:39 ` Christoph Hellwig
2025-10-29 6:05 ` Kundan Kumar
2025-10-29 6:09 ` Darrick J. Wong via Linux-f2fs-devel
2025-10-29 8:55 ` Christoph Hellwig
2025-11-07 9:24 ` Kundan Kumar
2025-11-07 13:37 ` Christoph Hellwig [this message]
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