From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 3DD446B000A for ; Fri, 23 Mar 2018 11:19:08 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id 2so6811894pft.4 for ; Fri, 23 Mar 2018 08:19:08 -0700 (PDT) Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-db5eur01on0135.outbound.protection.outlook.com. [104.47.2.135]) by mx.google.com with ESMTPS id h32-v6si8818266pld.217.2018.03.23.08.19.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 23 Mar 2018 08:19:06 -0700 (PDT) Subject: Re: [PATCH] mm, vmscan, tracing: Use pointer to reclaim_stat struct in trace event References: <20180322121003.4177af15@gandalf.local.home> <20180322141022.f02476e1f76338ab9cecf62e@linux-foundation.org> From: Andrey Ryabinin Message-ID: Date: Fri, 23 Mar 2018 18:19:48 +0300 MIME-Version: 1.0 In-Reply-To: <20180322141022.f02476e1f76338ab9cecf62e@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Steven Rostedt Cc: LKML , linux-mm@kvack.org, Michal Hocko , Mel Gorman , Vlastimil Babka , Linus Torvalds , Alexei Starovoitov On 03/23/2018 12:10 AM, Andrew Morton wrote: > On Thu, 22 Mar 2018 12:10:03 -0400 Steven Rostedt wrote: > >> >> The trace event trace_mm_vmscan_lru_shrink_inactive() currently has 12 >> parameters! Seven of them are from the reclaim_stat structure. This >> structure is currently local to mm/vmscan.c. By moving it to the global >> vmstat.h header, we can also reference it from the vmscan tracepoints. In >> moving it, it brings down the overhead of passing so many arguments to the >> trace event. In the future, we may limit the number of arguments that a >> trace event may pass (ideally just 6, but more realistically it may be 8). > > Unfortunately this is not a good time. Andrey's "mm/vmscan: replace > mm_vmscan_lru_shrink_inactive with shrink_page_list tracepoint" mucks > with this code quite a lot and that patch's series is undergoing review > at present, with a few issues yet unresolved. I slightly reworked my patch series, so that patch "mm/vmscan: replace mm_vmscan_lru_shrink_inactive with shrink_page_list tracepoint" is not needed anymore. Replacing that tracepoint with less informative shrink_page_list probably isn't a very good idea anyway. So Steven's patch applies *almost* cleanly on top of my v2, nothing that 3-way merge can't handle: # git am -3 mm-vmscan-tracing-Use-pointer-to-reclaim_stat-struct.patch Applying: mm, vmscan, tracing: Use pointer to reclaim_stat struct in trace event Using index info to reconstruct a base tree... M include/trace/events/vmscan.h M mm/vmscan.c Falling back to patching base and 3-way merge... Auto-merging mm/vmscan.c Auto-merging include/trace/events/vmscan.h