Re: [PATCH 3/3] mm: adjust vm_committed_as_batch according to vm overcommit policy

[Feng Tang]

On Fri, May 08, 2020 at 07:24:48PM +0800, Matthew Wilcox wrote:
> 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 ...

Yep, my bad, thanks for the catching, will remove it.

- Feng