Re: [RFC][PATCH 13/14] memcg: mem+swap counter

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

> @@ -279,6 +285,10 @@ static int mem_counter_charge(struct mem
>  	spin_lock_irqsave(&mem->res.lock, flags);
>  	if (mem->res.pages + num > mem->res.pages_limit)
>  		goto busy_out;
> +	if (do_swap_account &&
> +	    (mem->res.pages + mem->res.swaps > mem->res.memsw_limit))
                                           ^^^
You need "+ num" here.

> +		goto busy_out;
> +
>  	mem->res.pages += num;
>  	if (mem->res.pages > mem->res.max_pages)
>  		mem->res.max_pages = mem->res.pages;


> @@ -772,20 +831,28 @@ static int mem_cgroup_charge_common(stru
>  	}
>  
>  	while (mem_counter_charge(mem, 1)) {
> +		int progress;
>  		if (!(gfp_mask & __GFP_WAIT))
>  			goto out;
>  
> -		if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
> -			continue;
> +		progress = try_to_free_mem_cgroup_pages(mem, gfp_mask);
>  
>  		/*
> +		 * When we hit memsw limit, return value of "progress"
> +		 * has no meaning. (some pages may just be changed to swap)
> +		 */
> +		if (mem_counter_check_under_memsw_limit(mem) && progress)
> +			continue;
> +		/*
>  		 * try_to_free_mem_cgroup_pages() might not give us a full
>  		 * picture of reclaim. Some pages are reclaimed and might be
>  		 * moved to swap cache or just unmapped from the cgroup.
>  		 * Check the limit again to see if the reclaim reduced the
>  		 * current usage of the cgroup before giving up
>  		 */
> -		if (mem_counter_check_under_pages_limit(mem))
> +
> +		if (!do_swap_account
> +		   && mem_counter_check_under_pages_limit(mem))
>  			continue;
>  
>  		if (!nr_retries--) {
IMHO, try_to_free_mem_cgroup_pages() should use swap only when
!mem_counter_check_under_pages_limit(). Otherwise, it would
try to swapout some pages in vain.

How about adding a "may_swap" flag to args of tyr_to_free_mem_cgroup_pages(),
and pass the arg to sc->may_swap?


Thanks,
Daisuke Nishimura.

--
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/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>