Re: [PATCH 1/3] posix timers: Allocate timer id per process

From: Pavel Emelyanov
Date: Fri Feb 15 2013 - 00:14:08 EST

On 02/15/2013 12:13 AM, Sasha Levin wrote:
> On Thu, Feb 14, 2013 at 11:19 AM, Pavel Emelyanov <xemul@xxxxxxxxxxxxx> wrote:
>> From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
>> Patch replaces global idr with global hash table for posix timers and
>> makes timer ids unique not globally, but per process. 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 has 512 slots.
>> Key is constructed as follows:
>> key = hash_32(hash_32(current->signal) ^ posix_timer_id));
>> Note: with this patch, id, returned to user, is not the minimal free
>> amymore. It means, that id, returned to user space in loop, listed below, will
>> be increasing on each iteration till INT_MAX and then dropped to zero:
>> while(1) {
>> id = timer_create(...);
>> timer_delete(id);
>> }
>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
>> Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Hi Pavel,
> Why not use linux/hashtable.h?

Simply because this patch was just picked from the previous discussions
as is :) I will tune it to use hashtable.h in the next iteration.

> Thanks,
> Sasha
> .

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