* Re: [dm-devel] Questions about the function, queue_empty in dm-cache-policy-mq.c
[not found] <54AA03E0.9020900@gmail.com>
@ 2015-01-05 9:17 ` Joe Thornber
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From: Joe Thornber @ 2015-01-05 9:17 UTC (permalink / raw)
To: device-mapper development; +Cc: agk, linux-raid, linux-kernel, snitzer
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
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