Re: [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count
On 04/16/2013 06:05 AM, Will Deacon wrote: On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote: If it is confirmed that all the supported architectures can allow a negative mutex count without incorrect behavior, we can then back out the architecture specific change and allow the mutex count to go to any negative number. That should further reduce contention for non-x86 architecture. If this is not the case, this patch should be dropped. A good starting point might be to look at the asm-generic mutex implementations, which clears up the majority of architectures. A cursory glance at mutex-dec.h suggests that it's OK to me... I think the generic version is fine with negative mutex count. However, it is the architecture specific versions (we have 22 of them as of 3.8) that I am worry about. I just don't have enough know-how and test machines to verify that. Regards, Longman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count
On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote: > If it is confirmed that all the supported architectures can allow a > negative mutex count without incorrect behavior, we can then back > out the architecture specific change and allow the mutex count to > go to any negative number. That should further reduce contention for > non-x86 architecture. > > If this is not the case, this patch should be dropped. A good starting point might be to look at the asm-generic mutex implementations, which clears up the majority of architectures. A cursory glance at mutex-dec.h suggests that it's OK to me... Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count
On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote: If it is confirmed that all the supported architectures can allow a negative mutex count without incorrect behavior, we can then back out the architecture specific change and allow the mutex count to go to any negative number. That should further reduce contention for non-x86 architecture. If this is not the case, this patch should be dropped. A good starting point might be to look at the asm-generic mutex implementations, which clears up the majority of architectures. A cursory glance at mutex-dec.h suggests that it's OK to me... Will -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count
On 04/16/2013 06:05 AM, Will Deacon wrote: On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote: If it is confirmed that all the supported architectures can allow a negative mutex count without incorrect behavior, we can then back out the architecture specific change and allow the mutex count to go to any negative number. That should further reduce contention for non-x86 architecture. If this is not the case, this patch should be dropped. A good starting point might be to look at the asm-generic mutex implementations, which clears up the majority of architectures. A cursory glance at mutex-dec.h suggests that it's OK to me... I think the generic version is fine with negative mutex count. However, it is the architecture specific versions (we have 22 of them as of 3.8) that I am worry about. I just don't have enough know-how and test machines to verify that. Regards, Longman -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/