From: "ying.huang@intel.com" <ying.huang@intel.com>
To: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>,
Wei Xu <weixugc@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Thelen <gthelen@google.com>, Yang Shi <shy828301@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jagdish Gediya <jvgediya@linux.ibm.com>,
Michal Hocko <mhocko@kernel.org>,
Tim C Chen <tim.c.chen@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Alistair Popple <apopple@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Feng Tang <feng.tang@intel.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Dan Williams <dan.j.williams@intel.com>,
David Rientjes <rientjes@google.com>,
Linux MM <linux-mm@kvack.org>,
Brice Goglin <brice.goglin@gmail.com>,
Hesham Almatary <hesham.almatary@huawei.com>
Subject: Re: RFC: Memory Tiering Kernel Interfaces (v2)
Date: Thu, 12 May 2022 15:18:27 +0800 [thread overview]
Message-ID: <9c93f72ad70687d06e9318f8023ce45d39f742e3.camel@intel.com> (raw)
In-Reply-To: <c5d55131-76ff-7354-2954-7cfac365a9a5@linux.ibm.com>
On Thu, 2022-05-12 at 12:42 +0530, Aneesh Kumar K V wrote:
> On 5/12/22 12:33 PM, ying.huang@intel.com wrote:
> > On Wed, 2022-05-11 at 23:22 -0700, Wei Xu wrote:
> > > Sysfs Interfaces
> > > ================
> > >
> > > * /sys/devices/system/memtier/memtierN/nodelist
> > >
> > > where N = 0, 1, 2 (the kernel supports only 3 tiers for now).
> > >
> > > Format: node_list
> > >
> > > Read-only. When read, list the memory nodes in the specified tier.
> > >
> > > Tier 0 is the highest tier, while tier 2 is the lowest tier.
> > >
> > > The absolute value of a tier id number has no specific meaning.
> > > What matters is the relative order of the tier id numbers.
> > >
> > > When a memory tier has no nodes, the kernel can hide its memtier
> > > sysfs files.
> > >
> > > * /sys/devices/system/node/nodeN/memtier
> > >
> > > where N = 0, 1, ...
> > >
> > > Format: int or empty
> > >
> > > When read, list the memory tier that the node belongs to. Its value
> > > is empty for a CPU-only NUMA node.
> > >
> > > When written, the kernel moves the node into the specified memory
> > > tier if the move is allowed. The tier assignment of all other nodes
> > > are not affected.
> > >
> > > Initially, we can make this interface read-only.
> >
> > It seems that "/sys/devices/system/node/nodeN/memtier" has all
> > information we needed. Do we really need
> > "/sys/devices/system/memtier/memtierN/nodelist"?
> >
> > That can be gotten via a simple shell command line,
> >
> > $ grep . /sys/devices/system/node/nodeN/memtier | sort -n -k 2 -t ':'
> >
>
> It will be really useful to fetch the memory tier node list in an easy
> fashion rather than reading multiple sysfs directories. If we don't have
> other attributes for memorytier, we could keep
> "/sys/devices/system/memtier/memtierN" a NUMA node list there by
> avoiding /sys/devices/system/memtier/memtierN/nodelist
This will make the interface not extensible. Even a single file
"/sys/devices/system/node/memtiers" is better. As an readonly file, it
should be OK to put multiple values in it.
I remember that one rule for sysfs is that it is accessed more via
libsysfs. Does that make life easier?
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2022-05-12 7:19 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 6:22 RFC: Memory Tiering Kernel Interfaces (v2) Wei Xu
2022-05-12 7:03 ` ying.huang
2022-05-12 7:12 ` Aneesh Kumar K V
2022-05-12 7:18 ` ying.huang [this message]
2022-05-12 7:22 ` Wei Xu
2022-05-12 7:36 ` Aneesh Kumar K.V
2022-05-12 8:15 ` Wei Xu
2022-05-12 8:37 ` ying.huang
2022-05-13 2:52 ` ying.huang
2022-05-13 7:00 ` Wei Xu
2022-05-16 1:57 ` ying.huang
2022-05-12 21:12 ` Tim Chen
2022-05-12 21:31 ` Wei Xu
2022-05-12 15:00 ` Jonathan Cameron
2022-05-18 7:09 ` Wei Xu
2022-05-18 12:00 ` Jonathan Cameron
2022-05-24 7:36 ` Wei Xu
2022-05-24 13:26 ` Aneesh Kumar K.V
2022-05-25 5:27 ` Wei Xu
2022-05-25 7:47 ` Alistair Popple
2022-05-25 11:48 ` Jonathan Cameron
2022-05-25 15:32 ` Wei Xu
2022-05-20 3:06 ` Ying Huang
2022-05-24 7:04 ` Wei Xu
2022-05-24 8:24 ` Ying Huang
2022-05-25 5:32 ` Wei Xu
2022-05-25 9:03 ` Ying Huang
2022-05-25 10:01 ` Aneesh Kumar K V
2022-05-25 11:36 ` Mika Penttilä
2022-05-25 15:33 ` Wei Xu
2022-05-25 17:27 ` Wei Xu
2022-05-26 9:32 ` Jonathan Cameron
2022-05-26 20:30 ` Wei Xu
2022-05-27 9:26 ` Aneesh Kumar K V
2022-05-25 15:36 ` Wei Xu
2022-05-26 1:09 ` Ying Huang
2022-05-26 3:53 ` Wei Xu
2022-05-26 6:54 ` Ying Huang
2022-05-26 7:08 ` Wei Xu
2022-05-26 7:39 ` Ying Huang
2022-05-26 20:55 ` Wei Xu
2022-05-27 9:10 ` Jonathan Cameron
2022-05-30 6:54 ` Ying Huang
2022-05-13 3:25 ` ying.huang
2022-05-13 6:36 ` Wei Xu
2022-05-13 7:04 ` ying.huang
2022-05-13 7:21 ` Wei Xu
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