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Message-ID: <20140920052653.GB7926@mtj.dyndns.org> Date: Sat, 20 Sep 2014 01:26:53 -0400 From: Tejun Heo <tj@...nel.org> To: cl@...ux-foundation.org, kmo@...erainc.com Cc: linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org> Subject: Re: [PATCH 3/3] percpu-refcount: make percpu_ref based on longs instead of ints On Mon, Sep 08, 2014 at 11:12:22AM +0900, Tejun Heo wrote: > percpu_ref is currently based on ints and the number of refs it can > cover is (1 << 31). This makes it impossible to use a percpu_ref to > count memory objects or pages on 64bit machines as it may overflow. > This forces those users to somehow aggregate the references before > contributing to the percpu_ref which is often cumbersome and sometimes > challenging to get the same level of performance as using the > percpu_ref directly. > > While using ints for the percpu counters makes them pack tighter on > 64bit machines, the possible gain from using ints instead of longs is > extremely small compared to the overall gain from per-cpu operation. > This patch makes percpu_ref based on longs so that it can be used to > directly count memory objects or pages. > > Signed-off-by: Tejun Heo <tj@...nel.org> > Cc: Kent Overstreet <kmo@...erainc.com> > Cc: Johannes Weiner <hannes@...xchg.org> Applied 1 and 3 to percpu/for-3.18. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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