Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
Date:   Thu, 7 Dec 2023 19:11:59 -0500
From:   Gregory Price <gregory.price@memverge.com>
To:     Gregory Price <gourry.memverge@gmail.com>, linux-mm@kvack.org,
        jgroves@micron.com, ravis.opensrc@micron.com,
        sthanneeru@micron.com, emirakhur@micron.com, Hasan.Maruf@amd.com,
        linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        arnd@arndb.de, tglx@linutronix.de, luto@kernel.org,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        x86@kernel.org, hpa@zytor.com, mhocko@kernel.org, tj@kernel.org,
        ying.huang@intel.com, corbet@lwn.net, rakie.kim@sk.com,
        hyeongtak.ji@sk.com, honggyu.kim@sk.com, vtavarespetr@micron.com,
        peterz@infradead.org
Subject: Re: [RFC PATCH 01/11] mm/mempolicy: implement the sysfs-based
 weighted_interleave interface
Message-ID: <ZXJfT/EXFu+MtTkW@memverge.com>
References: <20231207002759.51418-1-gregory.price@memverge.com>
 <20231207002759.51418-2-gregory.price@memverge.com>
 <uxqkbmqbvcvx6wc3g2h6vhkutv5flrq6rslwdfs7pa6kknupwh@a245pbtfqfgj>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <uxqkbmqbvcvx6wc3g2h6vhkutv5flrq6rslwdfs7pa6kknupwh@a245pbtfqfgj>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?6kM1oHoIff6eXahaQ1lELhOknww9FIYINdzojy/W0zzEc5mqwbLRZuTOf6+1?=
 =?us-ascii?Q?aDr2ksgtXpEAFCvWL+dfvZuuC9iaJVqdIr8yhDhZ9Y/MpCZX4JBswwYRvaFN?=
 =?us-ascii?Q?GhMTkxdCaQyF/ZVp63UhU4/jpINPXA+lgI615CY4yHLl2qKLexDn/F0JLPzf?=
 =?us-ascii?Q?qfcMooDw5/dZ3d1SgdgaD30Pvvj4CbJroNBlFZJ4B+ypbb8w5cegACwApK1z?=
 =?us-ascii?Q?uzGBHaBMxd9Q/QEnKAiMT3YZlFVslLQWPtf46j1X2ebT0mCodZVpcOa+SqMT?=
 =?us-ascii?Q?yTsKKO11fySOm5yrJMNgKHR+gXZLBvClwDobY4BCX2xrSRYEzw9sAEL58Nig?=
 =?us-ascii?Q?5uZEzWZXVYOOJDVrF+srCorBZ4BCuZ4pbarVEZ8oM/e5gyLEeUkdDlGeRagH?=
 =?us-ascii?Q?IEXL2+cPpESiv5fZZ8RM5n1AHv61HHHSI7+mkB81brDLaHgMZgVJjPab37hK?=
 =?us-ascii?Q?1EwAAuGAZEWGAQxm7/3XwwpMWmV9jUMAtIBNa53nnU+7anvM3968CcLVFPaF?=
 =?us-ascii?Q?IhWVPEJOIWQLaDhuMItCzKX92EHw2QseV/hDMF0c6RKvSPOlTScWyEIPAuCz?=
 =?us-ascii?Q?aZ173fSGJeurU3133bNj0yunnGBc42UdDKfQuqp5AVbZK7hMW6ZheUT/3q62?=
 =?us-ascii?Q?dIo2nJ06XGYYf1FmzxoqP+UL92wQ9khl+LvKuo32qpJnpLKeB71VHXW3nXAK?=
 =?us-ascii?Q?HdpoP+vvH0jBQBTDqqJ16A47Pkh/j7DtCvit2+kpseTg8bjYI8BG9x3EWTfV?=
 =?us-ascii?Q?RaRSmBrETQiZpJnAE9Y3vFXSXl5prbZkPh4oRIUu9lvNqfYvuYzVvbFZ8mMt?=
 =?us-ascii?Q?xaoSrnMPpqaDzLynbxFEDmxc6oATfDtvMo19Pkw6cTrRPmF7hMyvb4oRyPv6?=
 =?us-ascii?Q?a5OM4a9qN4fqx0+FI2pyUJXapmNbMz84p6jjHeenIawkIqBnpVCjVDnsxgmW?=
 =?us-ascii?Q?XYzWDqaVNuzNVmb13Zr1nPOX8WB5wT9zuDxFUJVIOsaJulX+tjYrzZDHM4JJ?=
 =?us-ascii?Q?GJ/q8I8EpxG9960lKL3UKPi9FVpd5oI8AnLaWNb8XrE9Bt7YSXX/sMXEiBUe?=
 =?us-ascii?Q?mtiY2TKfRGfQKKfsy86nErka166e97THnFCaz+OQVXGxWaj8JfWwq+DVzHRB?=
 =?us-ascii?Q?RnrDVZDOpm2BCmd++Ag+mdFs4s+UYy8DzAFVNSfwAu3tpmaQdTpue8+xq7C9?=
 =?us-ascii?Q?acq7KWawGLyJGKFICLlNQL4Eq2pafcGMRPHR58B62RIhVDQiOrkcF68ko4VS?=
 =?us-ascii?Q?rpBx6xkfUCF1V31G16KOLNiKaE09W4OLKbyLhBipZejOO8+p9d7eUjjheH93?=
 =?us-ascii?Q?7LWwDQWCFrGN3CBn+M1Nk+OmmktPYE0SFuWmvetwqwiCH7Vv3GiBH8evBHaf?=
 =?us-ascii?Q?QwJx0/bnhlRTM1fjFdSh6IMdpzlHxaZqcoBUOk60kGcRL5mFmrxC5C/yiCJU?=
 =?us-ascii?Q?RH5gvicy6Lbyd4ZpVEXsvC0PWaKgZgNoQjzlpkUTm4qGUe+rymA1A6OsfvfX?=
 =?us-ascii?Q?nMyJLMfXiqDjXuDspMiO4P2mtPKV0VwfYFXYnPHOjQXDWz3nHX6TuA9td92i?=
 =?us-ascii?Q?qRpUrQW5xnHf/sqFdkxyDnzjt/NaB/1Fl5jLrmG7sz91cT7iAh3rFWIskOlQ?=
 =?us-ascii?Q?JQ=3D=3D?=
X-OriginatorOrg: memverge.com
X-MS-Exchange-CrossTenant-Network-Message-Id: efd1d4a4-66d9-4f90-627f-08dbf7824f4c
X-MS-Exchange-CrossTenant-AuthSource: SJ0PR17MB5512.namprd17.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Dec 2023 00:12:05.3240
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 5c90cb59-37e7-4c81-9c07-00473d5fb682
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: p+aHLrGHdKXqRCL4AufnaHHvk+iXpIjGJaodIPDN7Mfdnv14Mrnepe0YnoXRC1aCwnUGuHwYgkpM1jMU1voi30GYtLH7m5z9F3mMIsCTys0=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR17MB5843
X-Spam-Status: No, score=-0.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,SUBJECT_DRUG_GAP_L,
        T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Thu, 07 Dec 2023 16:12:18 -0800 (PST)

On Thu, Dec 07, 2023 at 01:56:07PM -0800, Davidlohr Bueso wrote:
> On Wed, 06 Dec 2023, Gregory Price wrote:
> > +
> > +What:		/sys/kernel/mm/mempolicy/weighted_interleave/nodeN/
> > +Date:		December 2023
> > +Contact:	Linux memory management mailing list <linux-mm@kvack.org>
> > +Description:	Configuration interface for accesses initiated from nodeN
> > +
> > +		The directory to configure access initiator weights for nodeN.
> > +
> > +		Possible numa nodes which have not been marked as a CPU node
> > +		at boot will not have a nodeN directory made for them at boot.
> 
> This could be better rephrased without the negation. ie:
> 
> "Only numa nodes with CPUs (compute) will have a nodeN directory."
> 

I thought documentation was supposed to be as confusing as possible.

lol I'll update it.  reading it now, this is awful.

> > +		Hotplug for CPU nodes is not supported.
> 
> Can this even happen? Hot-adding a previously offlined CPU won't change/add a
> new numa node. So just rm the line altogether?
>

I... have no idea.  In that sense, aye aye!

> > +static ssize_t node_weight_show(struct kobject *kobj,
> > +				struct kobj_attribute *attr, char *buf)
> > +
> > +static ssize_t node_weight_store(struct kobject *kobj,
> > +				 struct kobj_attribute *attr,
> > +				 const char *buf, size_t count)
> 
> iw_table will need some (basic) form of serialization.
> 

originally the SKH group recommended a serialized "N*W,N*W,..." format,
but this doesn't work for a matrix.

Possibly i could add `N-M*W,...;N-M*W,...` and add a nodeN/weightlist
interface that lets you acquire the whole iw_table for one or more
nodes.  Might be a nice extension.

I figured there is an aversion to multi-value sysfs files, so I reverted
back to a one-file-one-value file.  If there is a preference for the
fully serialized methods, I'll happily add those.  Easy enough and I
already have the code to parse it.

~Gregory