From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91BBCC77B73 for ; Tue, 2 May 2023 10:00:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233716AbjEBKAx (ORCPT ); Tue, 2 May 2023 06:00:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230004AbjEBKAu (ORCPT ); Tue, 2 May 2023 06:00:50 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA4FDF9 for ; Tue, 2 May 2023 03:00:49 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 639BD1F8BE; Tue, 2 May 2023 10:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1683021648; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EQGFmprAkf6SOGmZcALNchoLIXzx1I6PSxS66a6jet8=; b=xQ6JaecBwap2jvpIJ31SWlM85SFeS5pVbSmJrTo8OcH8F+BJl7Bn+3GZHGG4pRq3YgMFK7 UTSSsOlEhV5ox5haOFuEl/z9ln+zEQ49zYyjI0uz11RCqGbHwtULOI+FNLc+VdR6ZC9bTg /5k3CGJ3kuqBHRJ+CFo/uavxNGinkOQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1683021648; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EQGFmprAkf6SOGmZcALNchoLIXzx1I6PSxS66a6jet8=; b=FquHuOLlZRQgEkHms/NYY7NkRXmeTQlbefmtFXMHofFnlEWcLdee1WSLeDp4v9FRmyYbwh GUYS/XhGVKDhFeDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4681C139C3; Tue, 2 May 2023 10:00:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id fqmEEFDfUGTlZwAAMHmgww (envelope-from ); Tue, 02 May 2023 10:00:48 +0000 Message-ID: Date: Tue, 2 May 2023 12:00:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH 1/1] mm: change per-VMA lock statistics to be disabled by default Content-Language: en-US To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: torvalds@linux-foundation.org, lstoakes@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com References: <20230428173533.18158-1-surenb@google.com> From: Vlastimil Babka In-Reply-To: <20230428173533.18158-1-surenb@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/28/23 19:35, Suren Baghdasaryan wrote: > Change CONFIG_PER_VMA_LOCK_STATS to be disabled by default, as most > users don't need it. Add configuration help to clarify its usage. > > Fixes: 52f238653e45 ("mm: introduce per-VMA lock statistics") > Suggested-by: Linus Torvalds > Signed-off-by: Suren Baghdasaryan Acked-by: Vlastimil Babka > --- > mm/Kconfig.debug | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 6dae63b46368..a925415b4d10 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -274,6 +274,12 @@ config DEBUG_KMEMLEAK_AUTO_SCAN > config PER_VMA_LOCK_STATS > bool "Statistics for per-vma locks" > depends on PER_VMA_LOCK > - default y > help > - Statistics for per-vma locks. > + Say Y here to enable success, retry and failure counters of page > + faults handled under protection of per-vma locks. When enabled, the > + counters are exposed in /proc/vmstat. This information is useful for > + kernel developers to evaluate effectiveness of per-vma locks and to > + identify pathological cases. Counting these events introduces a small > + overhead in the page fault path. > + > + If in doubt, say N.