[Devel] [PATCH 0/7] drivers/md/dm-qcow2: per-qio fast path

From: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
To: ptikhomirov@virtuozzo.com, alexander.ivanov@virtuozzo.com
Cc: devel@openvz.org
Subject: [Devel] [PATCH 0/7] drivers/md/dm-qcow2: per-qio fast path
Date: Thu, 29 Oct 2026 17:03:39 +0300	[thread overview]
Message-ID: <20261029140346.465768-1-andrey.zhadchenko@virtuozzo.com> (raw)

dm-qcow2 processes every request consequentially in a single kwork.
Unfortunately this introduces latency and cpu-bound limits. This
patchset addresses the problem by laying per-qio tasks foundation:
qios can be executed in parallel on the same workqueue. For now cover
only requests with metadata fully allocated.

https://virtuozzo.atlassian.net/browse/VSTOR-95494

Andrey Zhadchenko (7):
  drivers/md/dm-qcow2: repeat md page lookup if it was inserted in
    parallel
  drivers/md/dm-qcow2: check MD_DIRTY and md->wbd under lock in
    perform_rw_mapped()
  drivers/md/dm-qcow2: prepare process_one_qio() for fastpath
  drivers/md/dm-qcow2: add per-qio work infrastructure
  drivers/md/dm-qcow2: implement per-qio fast processing
  drivers/md/dm-qcow2: declare DM_TARGET_NOWAIT
  drivers/md/dm-qcow2: process fast path qios in per-cpu batches on a
    workqueue

 drivers/md/dm-qcow2-map.c    | 214 +++++++++++++++++++++++++++++------
 drivers/md/dm-qcow2-target.c |  12 +-
 drivers/md/dm-qcow2.h        |  10 ++
 3 files changed, 197 insertions(+), 39 deletions(-)

-- 
2.43.5

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