From: jgunthorpe@obsidianresearch.com (Jason Gunthorpe)
Subject: [PATCH v4, under testing] nvme-rdma: support devices with queue size < 32
Date: Wed, 3 May 2017 09:53:16 -0600 [thread overview]
Message-ID: <20170503155316.GA14334@obsidianresearch.com> (raw)
In-Reply-To: <780938034.8003164.1493824767084.JavaMail.zimbra@kalray.eu>
On Wed, May 03, 2017@05:19:27PM +0200, Marta Rybczynska wrote:
> > where
> > queue->sig_limit = max(queue->queue_size / 2, 1);
>
> I tried to avoid that because this adds a division in the fast path Bart
> was unhappy about in v2.
The compiler switches divide/multiply by powers of two into fast bit shifts.
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Marta Rybczynska <mrybczyn-FNhOzJFKnXGHXe+LvDLADg@public.gmane.org>
Cc: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
axboe-b10kYP2dOMg@public.gmane.org,
Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
Keith Busch <keith.busch-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Bart Van Assche
<bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>,
samuel jones
<samuel.jones-FNhOzJFKnXGHXe+LvDLADg@public.gmane.org>
Subject: Re: [PATCH v4, under testing] nvme-rdma: support devices with queue size < 32
Date: Wed, 3 May 2017 09:53:16 -0600 [thread overview]
Message-ID: <20170503155316.GA14334@obsidianresearch.com> (raw)
In-Reply-To: <780938034.8003164.1493824767084.JavaMail.zimbra-FNhOzJFKnXGHXe+LvDLADg@public.gmane.org>
On Wed, May 03, 2017 at 05:19:27PM +0200, Marta Rybczynska wrote:
> > where
> > queue->sig_limit = max(queue->queue_size / 2, 1);
>
> I tried to avoid that because this adds a division in the fast path Bart
> was unhappy about in v2.
The compiler switches divide/multiply by powers of two into fast bit shifts.
Jason
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next prev parent reply other threads:[~2017-05-03 15:53 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-03 10:05 [PATCH v4, under testing] nvme-rdma: support devices with queue size < 32 Marta Rybczynska
2017-05-03 10:05 ` Marta Rybczynska
2017-05-03 11:17 ` Leon Romanovsky
2017-05-03 11:17 ` Leon Romanovsky
2017-05-03 15:08 ` Sagi Grimberg
2017-05-03 15:08 ` Sagi Grimberg
2017-05-03 15:19 ` Marta Rybczynska
2017-05-03 15:19 ` Marta Rybczynska
2017-05-03 15:45 ` Bart Van Assche
2017-05-03 15:45 ` Bart Van Assche
2017-05-03 15:53 ` Jason Gunthorpe [this message]
2017-05-03 15:53 ` Jason Gunthorpe
2017-05-03 15:58 ` Bart Van Assche
2017-05-03 15:58 ` Bart Van Assche
2017-05-03 16:01 ` Sagi Grimberg
2017-05-03 16:01 ` Sagi Grimberg
2017-05-03 16:27 ` Leon Romanovsky
2017-05-03 16:27 ` Leon Romanovsky
2017-05-03 16:37 ` Bart Van Assche
2017-05-03 16:37 ` Bart Van Assche
2017-05-03 16:49 ` Sagi Grimberg
2017-05-03 16:49 ` Sagi Grimberg
2017-05-04 12:50 ` Marta Rybczynska
2017-05-04 12:50 ` Marta Rybczynska
2017-05-17 9:02 ` Christoph Hellwig
2017-05-17 9:02 ` Christoph Hellwig
2017-05-17 12:50 ` Marta Rybczynska
2017-05-17 12:50 ` Marta Rybczynska
2017-05-03 16:17 ` Doug Ledford
2017-05-03 16:17 ` Doug Ledford
2017-05-03 16:24 ` Bart Van Assche
2017-05-03 16:24 ` Bart Van Assche
2017-05-03 19:07 ` Doug Ledford
2017-05-03 19:07 ` Doug Ledford
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