Re: [PATCH 3/3] mm: adjust vm_committed_as_batch according to vm overcommit policy
From: Matthew Wilcox
Date: Fri May 08 2020 - 07:24:59 EST
On Fri, May 08, 2020 at 03:25:17PM +0800, Feng Tang wrote:
> +void mm_compute_batch(void)
> {
> u64 memsized_batch;
> s32 nr = num_present_cpus();
> s32 batch = max_t(s32, nr*2, 32);
> -
> - /* batch size set to 0.4% of (total memory/#cpus), or max int32 */
> - memsized_batch = min_t(u64, (totalram_pages()/nr)/256, 0x7fffffff);
> + unsigned long ram_pages = totalram_pages();
> +
> + /*
> + * For policy of OVERCOMMIT_NEVER, set batch size to 0.4%
> + * of (total memory/#cpus), and lift it to 6.25% for other
> + * policies to easy the possible lock contention for percpu_counter
> + * vm_committed_as, while the max limit is INT_MAX
> + */
> + if (sysctl_overcommit_memory == OVERCOMMIT_NEVER)
> + memsized_batch = min_t(u64, ram_pages/nr/256, INT_MAX);
> + else
> + memsized_batch = min_t(u64, ram_pages/nr/16, INT_MAX);
>
> vm_committed_as_batch = max_t(s32, memsized_batch, batch);
> + printk("vm_committed_as_batch = %d\n", vm_committed_as_batch);
> }
You left a debugging printk in ...