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Wed, 27 Oct 2021 13:06:40 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.180]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D593562A41; Wed, 27 Oct 2021 13:06:38 +0000 (UTC) Date: Wed, 27 Oct 2021 15:06:37 +0200 From: Kevin Wolf To: Stefano Garzarella Subject: Re: [PATCH v2 1/3] file-posix: add `aio-max-batch` option Message-ID: References: <20211026162346.253081-1-sgarzare@redhat.com> <20211026162346.253081-2-sgarzare@redhat.com> <87zgqvccqk.fsf@dusky.pond.sub.org> <20211027092304.43zhzjp5u6x66nbq@steredhat> MIME-Version: 1.0 In-Reply-To: <20211027092304.43zhzjp5u6x66nbq@steredhat> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org, Markus Armbruster , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 27.10.2021 um 11:23 hat Stefano Garzarella geschrieben: > On Wed, Oct 27, 2021 at 06:28:51AM +0200, Markus Armbruster wrote: > > Stefano Garzarella writes: > > > > > Commit d7ddd0a161 ("linux-aio: limit the batch size using > > > `aio-max-batch` parameter") added a way to limit the batch size > > > of Linux AIO backend for the entire AIO context. > > > > > > The same AIO context can be shared by multiple devices, so > > > latency-sensitive devices may want to limit the batch size even > > > more to avoid increasing latency. > > > > > > For this reason we add the `aio-max-batch` option to the file > > > backend, which will be used by the next commits to limit the size of > > > batches including requests generated by this device. > > > > > > Suggested-by: Kevin Wolf > > > Reviewed-by: Kevin Wolf > > > Signed-off-by: Stefano Garzarella > > > --- > > > > > > Notes: > > > v2: > > > - @aio-max-batch documentation rewrite [Stefan, Kevin] > > > > > > qapi/block-core.json | 7 +++++++ > > > block/file-posix.c | 9 +++++++++ > > > 2 files changed, 16 insertions(+) > > > > > > diff --git a/qapi/block-core.json b/qapi/block-core.json > > > index 6d3217abb6..fef76b0ea2 100644 > > > --- a/qapi/block-core.json > > > +++ b/qapi/block-core.json > > > @@ -2896,6 +2896,12 @@ > > > # for this device (default: none, forward the commands via SG_IO; > > > # since 2.11) > > > # @aio: AIO backend (default: threads) (since: 2.8) > > > +# @aio-max-batch: maximum number of requests to batch together into a single > > > +# submission in the AIO backend. The smallest value between > > > +# this and the aio-max-batch value of the IOThread object is > > > +# chosen. > > > +# 0 means that the AIO backend will handle it automatically. > > > +# (default: 0, since 6.2) > > > > "(default 0) (since 6.2)" seems to be more common. > > Indeed I wasn't sure, so I followed @drop-cache, the last one added in > @BlockdevOptionsFile. Actually, I think your style is more common, both globally and in block-*: $ git grep -i '[,;] since' qapi/ | wc -l 17 $ git grep -i '[,;] since' qapi/block* | wc -l 12 Compared to: $ git grep -i ') (since' qapi/ | wc -l 14 $ git grep -i ') (since' qapi/block* | wc -l 7 Also a few instances with "(since: ...; default: ...)", but none in that order with separate brackets. So I'd rather merge this version if this is the only comment. Kevin