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X-CSE-ConnectionGUID: FSOB5s00SxuxQBJWRgMiyw== X-CSE-MsgGUID: O0z6CidySu2qxa2cio2sRw== X-IronPort-AV: E=McAfee;i="6700,10204,11126"; a="17234105" X-IronPort-AV: E=Sophos;i="6.09,191,1716274800"; d="scan'208";a="17234105" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2024 19:09:59 -0700 X-CSE-ConnectionGUID: lD7LPvPlQcSO5Z3geuux7w== X-CSE-MsgGUID: Q1fUjy21TCWmG69T/QD65A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,191,1716274800"; d="scan'208";a="52181108" Received: from unknown (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2024 19:09:56 -0700 From: "Huang, Ying" To: Tvrtko Ursulin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-dev@igalia.com, Tvrtko Ursulin , Mel Gorman , Peter Zijlstra , Ingo Molnar , Rik van Riel , Johannes Weiner , "Matthew Wilcox (Oracle)" , Dave Hansen , Andi Kleen , Michal Hocko , David Rientjes , stable@vger.kernel.org Subject: Re: [PATCH 1/3] mm/numa_balancing: Teach mpol_to_str about the balancing mode In-Reply-To: <20240705143218.21258-2-tursulin@igalia.com> (Tvrtko Ursulin's message of "Fri, 5 Jul 2024 15:32:16 +0100") References: <20240705143218.21258-1-tursulin@igalia.com> <20240705143218.21258-2-tursulin@igalia.com> Date: Mon, 08 Jul 2024 10:08:05 +0800 Message-ID: <874j90eiuy.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: i3983kbj5gx5717k5ma95djigmtmff6m X-Rspamd-Queue-Id: 63F83120014 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1720404601-811078 X-HE-Meta: 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 oJ+aIIC8 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Tvrtko Ursulin writes: > From: Tvrtko Ursulin > > Since balancing mode was added in > bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes"), > it was possible to set this mode but it wouldn't be shown in > /proc//numa_maps since there was no support for it in the > mpol_to_str() helper. > > Furthermore, because the balancing mode sets the MPOL_F_MORON flag, it > would be displayed as 'default' due a workaround introduced a few years > earlier in > 8790c71a18e5 ("mm/mempolicy.c: fix mempolicy printing in numa_maps"). > > To tidy this up we implement two changes: > > Replace the MPOL_F_MORON check by pointer comparison against the > preferred_node_policy array. By doing this we generalise the current > special casing and replace the incorrect 'default' with the correct > 'bind' for the mode. > > Secondly, we add a string representation and corresponding handling for > the MPOL_F_NUMA_BALANCING flag. > > With the two changes together we start showing the balancing flag when it > is set and therefore complete the fix. > > Representation format chosen is to separate multiple flags with vertical > bars, following what existed long time ago in kernel 2.6.25. But as > between then and now there wasn't a way to display multiple flags, this > patch does not change the format in practice. > > Some /proc//numa_maps output examples: > > 555559580000 bind=balancing:0-1,3 file=... > 555585800000 bind=balancing|static:0,2 file=... > 555635240000 prefer=relative:0 file= > > v2: > * Fully fix by introducing MPOL_F_KERNEL. > > v3: > * Abandoned the MPOL_F_KERNEL approach in favour of pointer comparisons. > * Removed lookup generalisation for easier backporting. > * Replaced commas as separator with vertical bars. > * Added a few more words about the string format in the commit message. > > Signed-off-by: Tvrtko Ursulin > Fixes: bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes") > References: 8790c71a18e5 ("mm/mempolicy.c: fix mempolicy printing in numa_maps") > Cc: Huang Ying > Cc: Mel Gorman > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: Rik van Riel > Cc: Johannes Weiner > Cc: "Matthew Wilcox (Oracle)" > Cc: Dave Hansen > Cc: Andi Kleen > Cc: Michal Hocko > Cc: David Rientjes > Cc: # v5.12+ > --- > mm/mempolicy.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index aec756ae5637..1bfb6c73a39c 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -3293,8 +3293,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) > * @pol: pointer to mempolicy to be formatted > * > * Convert @pol into a string. If @buffer is too short, truncate the string. > - * Recommend a @maxlen of at least 32 for the longest mode, "interleave", the > - * longest flag, "relative", and to display at least a few node ids. > + * Recommend a @maxlen of at least 42 for the longest mode, "weighted > + * interleave", the longest flag, "balancing", and to display at least a few And we may display 2 flags now, +9 further? > + * node ids. > */ > void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) > { > @@ -3303,7 +3304,10 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) > unsigned short mode = MPOL_DEFAULT; > unsigned short flags = 0; > > - if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) { > + if (pol && > + pol != &default_policy && > + !(pol >= &preferred_node_policy[0] && > + pol <= &preferred_node_policy[MAX_NUMNODES - 1])) { Better to replace MAX_NUMNODES with ARRAY_SIZE() here. > mode = pol->mode; > flags = pol->flags; > } > @@ -3331,12 +3335,18 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) > p += snprintf(p, buffer + maxlen - p, "="); > > /* > - * Currently, the only defined flags are mutually exclusive > + * Static and relative are mutually exclusive. > */ > if (flags & MPOL_F_STATIC_NODES) > p += snprintf(p, buffer + maxlen - p, "static"); > else if (flags & MPOL_F_RELATIVE_NODES) > p += snprintf(p, buffer + maxlen - p, "relative"); > + > + if (flags & MPOL_F_NUMA_BALANCING) { > + if (hweight16(flags & MPOL_MODE_FLAGS) > 1) > + p += snprintf(p, buffer + maxlen - p, "|"); > + p += snprintf(p, buffer + maxlen - p, "balancing"); > + } Still think that it's better to move this part to [2/3]. Unless you can make the change small and the resulting code looks good. > } > > if (!nodes_empty(nodes)) -- Best Regards, Huang, Ying