From: Joe Thornber <thornber@redhat.com>
To: device-mapper development <dm-devel@redhat.com>
Cc: agk@redhat.com, linux-raid@vger.kernel.org,
linux-kernel@vger.kernel.org, snitzer@redhat.com
Subject: Re: [dm-devel] Questions about the function, queue_empty in dm-cache-policy-mq.c
Date: Mon, 5 Jan 2015 09:17:08 +0000 [thread overview]
Message-ID: <20150105091707.GA11818@debian> (raw)
In-Reply-To: <54AA03E0.9020900@gmail.com>
On Sun, Jan 04, 2015 at 10:24:16PM -0500, nick wrote:
> Greetings All,
> I have a few questions about the function I stated in the message for this email.
> 1. What is the issues with the CPU usage for this function?
At the moment it can perform up to NR_QUEUE_LEVELS (16) list_empty()
calls. Which I consider too much work for a function that is called
frequently.
> 2. What hardware is this on ?
Irrelevant.
> 3. How scalable is this function in terms of NR_QUEUE_LEVELS and how many does it need to handle?
Linear. NR_QUEUE_LEVELS is a compile time constant currently set to
16, and unlikely to change.
- Joe
prev parent reply other threads:[~2015-01-05 9:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-05 3:24 Questions about the function, queue_empty in dm-cache-policy-mq.c nick
2015-01-05 9:17 ` Joe Thornber [this message]
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