From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 2A1D26810B5 for ; Tue, 11 Jul 2017 14:25:39 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id e199so195686pfh.7 for ; Tue, 11 Jul 2017 11:25:39 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id i196si2672pgd.419.2017.07.11.11.25.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Jul 2017 11:25:38 -0700 (PDT) Subject: Re: [PATCH -mm -v2 2/6] mm, swap: Add swap readahead hit statistics References: <20170630014443.23983-1-ying.huang@intel.com> <20170630014443.23983-3-ying.huang@intel.com> From: Dave Hansen Message-ID: <1152d4f5-fe8b-b46c-9d6b-3ecf69019172@intel.com> Date: Tue, 11 Jul 2017 11:25:36 -0700 MIME-Version: 1.0 In-Reply-To: <20170630014443.23983-3-ying.huang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Huang, Ying" , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Rik van Riel , Shaohua Li , Hugh Dickins , Fengguang Wu , Tim Chen On 06/29/2017 06:44 PM, Huang, Ying wrote: > > static atomic_t swapin_readahead_hits = ATOMIC_INIT(4); > +static atomic_long_t swapin_readahead_hits_total = ATOMIC_INIT(0); > +static atomic_long_t swapin_readahead_total = ATOMIC_INIT(0); > > void show_swap_cache_info(void) > { > @@ -305,8 +307,10 @@ struct page * lookup_swap_cache(swp_entry_t entry) > > if (page && likely(!PageTransCompound(page))) { > INC_CACHE_INFO(find_success); > - if (TestClearPageReadahead(page)) > + if (TestClearPageReadahead(page)) { > atomic_inc(&swapin_readahead_hits); > + atomic_long_inc(&swapin_readahead_hits_total); > + } > } Adding global atomics that we touch in hot paths seems like poor future-proofing. Are we sure we want to do this and not use some of the nice, fancy, percpu counters that we have? -- 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: email@kvack.org