Messages in this thread | | | Date | Thu, 22 Dec 2011 14:20:58 -0800 | From | Andrew Morton <> | Subject | Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock |
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On Thu, 22 Dec 2011 14:09:11 -0800 Tejun Heo <tj@kernel.org> wrote:
> Hello, > > On Thu, Dec 22, 2011 at 01:59:25PM -0800, Andrew Morton wrote: > > How about we just delete those statistics and then this patchset? > > > > Or how about we change those statistics to not do percpu allocations, > > then delete this patchset? > > I'm not against above both
Don't just consider my suggestions - please try to come up with your own alternatives too! If all else fails then this patch is a last resort.
> but apparently those percpu stats reduced > CPU overhead significantly.
Deleting them would save even more CPU.
Or make them runtime or compile-time configurable, so only the developers see the impact.
Some specifics on which counters are causing the problems would help here.
> > Or how about we fix the percpu memory allocation code so that it > > propagates the gfp flags, then delete this patchset? > > Oh, no, this is gonna make things *way* more complex. I tried.
But there's a difference between fixing a problem and working around it.
> If > we're gonna have many more NOIO percpu users, which I don't think we > would or should, that might make sense but, for fringe cases, > extending mempool to cover percpu is a much better sized solution.
I've long felt that we goofed with the gfp_flags thing and that it should be a field in the task_struct. Now *that* would be a large patch!
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