Re: [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush
From: Gilad Ben-Yossef <gilad@benyossef.com>
Date: 2012-01-01 16:12:14
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On Sun, Jan 1, 2012 at 2:41 PM, Avi Kivity [off-list ref] wrote:
On 11/23/2011 08:23 AM, Pekka Enberg wrote:quoted
On Tue, 22 Nov 2011, Gilad Ben-Yossef wrote:quoted
static void flush_all(struct kmem_cache *s) { - on_each_cpu(flush_cpu_slab, s, 1); + cpumask_var_t cpus; + struct kmem_cache_cpu *c; + int cpu; + + if (likely(zalloc_cpumask_var(&cpus, GFP_ATOMIC))) {__GFP_NOWARN too maybe?quoted
+ for_each_online_cpu(cpu) { + c = per_cpu_ptr(s->cpu_slab, cpu); + if (c->page) + cpumask_set_cpu(cpu, cpus); + } + on_each_cpu_mask(cpus, flush_cpu_slab, s, 1); + free_cpumask_var(cpus); + } else + on_each_cpu(flush_cpu_slab, s, 1); }Since this seems to be a common pattern, how about: zalloc_cpumask_var_or_all_online_cpus(&cpus, GFTP_ATOMIC); ... free_cpumask_var(cpus); The long-named function at the top of the block either returns a newly allocated zeroed cpumask, or a static cpumask with all online cpus set. The code in the middle is only allowed to set bits in the cpumask (should be the common usage). free_cpumask_var() needs to check whether the freed object is the static variable.
Thanks for the feedback and advice! I totally agree the repeating pattern needs abstracting. I ended up chosing to try a different abstraction though - basically a wrapper on_each_cpu_cond that gets a predicate function to run per CPU to build the mask to send the IPI to. It seems cleaner to me not having to mess with free_cpumask_var and it abstracts more of the general pattern. I intend to run the new code through some more testing tomorrow and send out V5 of the patch set. I'd be delighted if you can have a look through it then. Thanks! Gilad -- Gilad Ben-Yossef Chief Coffee Drinker gilad@benyossef.com Israel Cell: +972-52-8260388 US Cell: +1-973-8260388 http://benyossef.com "Unfortunately, cache misses are an equal opportunity pain provider." -- Mike Galbraith, LKML -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>