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Re: [RFC PATCH] posix timers: allocate timer id per task [message #48363 is a reply to message #48361]

Mon, 15 October 2012 17:04

Peter Zijlstra
Messages: 61
Registered: September 2006

Member

On Mon, 2012-10-15 at 20:17 +0400, Stanislav Kinsbursky wrote:
> This patch is required CRIU project (www.criu.org).
> To migrate processes with posix timers we have to make sure, that we can
> restore posix timer with proper id.
> Currently, this is not true, because timer ids are allocated globally.
> So, this is precursor patch and it's purpose is make posix timer id to be
> allocated per task.
>
> Patch replaces global idr with global hash table for posix timers and
> makes timer ids unique not globally, but per task. Next free timer id is type
> of integer and stored on signal struct (posix_timer_id). If free timer id
> reaches negative value on timer creation, it will be dropped to zero and
> -EAGAIN will be returned to user.
> Hash table is size of page (4KB).
> Key is constructed as follows:
> key = hash_ptr(current->signal) ^ hash_32(posix_timer_id);

but but but.. isn't this what namespaces were invented for to solve? Why
not use the regular namespace infrastructure?

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[Message index]

		[RFC PATCH] posix timers: allocate timer id per task By: Stanislav Kinsbursky on Mon, 15 October 2012 16:17
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Eric Dumazet on Mon, 15 October 2012 16:34
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Stanislav Kinsbursky on Tue, 16 October 2012 07:57
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Peter Zijlstra on Mon, 15 October 2012 17:04
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Stanislav Kinsbursky on Tue, 16 October 2012 08:00
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Thomas Gleixner on Mon, 15 October 2012 19:08
		Re: [RFC PATCH] posix timers: allocate timer id per task By: Stanislav Kinsbursky on Tue, 16 October 2012 08:08

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