* Questions about the function, queue_empty in dm-cache-policy-mq.c
@ 2015-01-05 3:24 nick
2015-01-05 9:17 ` [dm-devel] " Joe Thornber
0 siblings, 1 reply; 2+ messages in thread
From: nick @ 2015-01-05 3:24 UTC (permalink / raw)
To: agk; +Cc: linux-raid, dm-devel, linux-kernel, snitzer
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?
2. What hardware is this on ?
3. How scalable is this function in terms of NR_QUEUE_LEVELS and how many does it need to handle?
Nick
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [dm-devel] Questions about the function, queue_empty in dm-cache-policy-mq.c
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
0 siblings, 0 replies; 2+ messages in thread
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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2015-01-05 3:24 Questions about the function, queue_empty in dm-cache-policy-mq.c nick
2015-01-05 9:17 ` [dm-devel] " Joe Thornber
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