linux-kernel - Re: [PATCH v7 13/13] vmstat: add pcp remote node draining via cpu_vm_stats

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Message-ID: <93b293341866a4366b2f2a614f8742ca94ff4e3c.camel@linux.intel.com>
Date:   Mon, 20 Mar 2023 13:43:09 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Marcelo Tosatti <mtosatti@...hat.com>,
        Christoph Lameter <cl@...ux.com>
Cc:     Aaron Tomlin <atomlin@...mlin.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Russell King <linux@...linux.org.uk>,
        Huacai Chen <chenhuacai@...nel.org>,
        Heiko Carstens <hca@...ux.ibm.com>, x86@...nel.org,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v7 13/13] vmstat: add pcp remote node draining via
 cpu_vm_stats_fold

On Mon, 2023-03-20 at 15:03 -0300, Marcelo Tosatti wrote:
> 
> +
> +		if (do_pagesets) {
> +			cond_resched();
> +			/*
> +			 * Deal with draining the remote pageset of a
> +			 * processor
> +			 *
> +			 * Check if there are pages remaining in this pageset
> +			 * if not then there is nothing to expire.
> +			 */
> +			if (!pcp->expire || !pcp->count)
> +				continue;refresh_cpu_vm_stats
> +
> +			/*
> +			 * We never drain zones local to this processor.
> +			 */
> +			if (zone_to_nid(zone) == cpu_to_node(cpu)) {
> +				pcp->expire = 0;
> +				continue;
> +			}
> +
> +			WARN_ON(pcp->expire < 0);
> +			/*
> +			 * pcp->expire is only accessed from vmstat_shepherd context,
> +			 * therefore no locking is required.
> +			 */
> +			if (--pcp->expire)
> +				continue;
> +
> +			if (pcp->count)
> +				drain_zone_pages(zone, pcp);
> +		}

This logic is the same to that for the do_pagesets portion of code in refresh_cpu_vm_stats().
Is it possible to consolidate to avoid replicating the logic across two functions?

Tim