From: Stephen Hemminger <stephen@networkplumber.org>
To: Long Li <longli@linuxonhyperv.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>,
linux-scsi@vger.kernel.org,
"Martin K . Petersen" <martin.petersen@oracle.com>,
"James E . J . Bottomley" <JBottomley@odin.com>,
linux-kernel@vger.kernel.org, devel@linuxdriverproject.org,
Haiyang Zhang <haiyangz@microsoft.com>
Subject: Re: [Patch v2] Storvsc: Select channel based on available percentage of ring buffer to write
Date: Fri, 20 Apr 2018 08:50:43 -0700 [thread overview]
Message-ID: <20180420085043.3a678b89@xeon-e3> (raw)
In-Reply-To: <20180419215424.3557-1-longli@linuxonhyperv.com>
On Thu, 19 Apr 2018 14:54:24 -0700
Long Li <longli@linuxonhyperv.com> wrote:
> From: Long Li <longli@microsoft.com>
>
> This is a best effort for estimating on how busy the ring buffer is for
> that channel, based on available buffer to write in percentage. It is still
> possible that at the time of actual ring buffer write, the space may not be
> available due to other processes may be writing at the time.
>
> Selecting a channel based on how full it is can reduce the possibility that
> a ring buffer write will fail, and avoid the situation a channel is over
> busy.
>
> Now it's possible that storvsc can use a smaller ring buffer size
> (e.g. 40k bytes) to take advantage of cache locality.
>
> Changes.
> v2: Pre-allocate struct cpumask on the heap.
> Struct cpumask is a big structure (1k bytes) when CONFIG_NR_CPUS=8192 (default
> value when CONFIG_MAXSMP=y). Don't use kernel stack for it by pre-allocating
> them using kmalloc when channels are first initialized.
>
> Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Stephen Hemminger <sthemmin@microsoft.com>
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next prev parent reply other threads:[~2018-04-20 15:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-19 21:54 [Patch v2] Storvsc: Select channel based on available percentage of ring buffer to write Long Li
2018-04-20 15:50 ` Stephen Hemminger [this message]
2018-04-20 19:40 ` Martin K. Petersen
2018-04-22 18:53 ` Michael Kelley (EOSG)
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