From: David Hildenbrand <david@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"Verma, Vishal L" <vishal.l.verma@intel.com>,
Wu Fengguang <fengguang.wu@intel.com>,
Huang Ying <ying.huang@intel.com>
Subject: Re: [RFC] Memory Tiering
Date: Thu, 17 Oct 2019 10:07:07 +0200 [thread overview]
Message-ID: <0679872d-3d03-2fa3-5bd2-80f694357203@redhat.com> (raw)
In-Reply-To: <c3d6de4d-f7c3-b505-2e64-8ee5f70b2118@intel.com>
On 16.10.19 22:05, Dave Hansen wrote:
> The memory hierarchy is getting more complicated and the kernel is
> playing an increasing role in managing the different tiers. A few
> different groups of folks described "migration" optimizations they were
> doing in this area at LSF/MM earlier this year. One of the questions
> folks asked was why autonuma wasn't being used.
>
> At Intel, the primary new tier that we're looking at is persistent
> memory (PMEM). We'd like to be able to use "persistent memory"
> *without* using its persistence properties, treating it as slightly
> slower DRAM. Keith Busch has some patches to use NUMA migration to
> automatically migrate DRAM->PMEM instead of discarding it near the end
> of the reclaim process. Huang Ying has some patches which use a
> modified autonuma to migrate frequently-used data *back* from PMEM->DRAM.
Very interesting topic. I heard similar demand from HPC folks
(especially involving other memory types ("tiers")). There, I think you
often want to let the application manage that. But of course, for many
applications an automatic management might already be beneficial.
Am I correct that you are using PMEM in this area along with ZONE_DEVICE
and not by giving PMEM to the buddy (add_memory())?
>
> We've tried to do this all generically so that it is not tied to
> persistent memory and can be applied to any memory types in lots of
> topologies.
>
> We've been running this code in various forms for the past few months,
> comparing it to pure DRAM and hardware-based caching. The initial
> results are encouraging and we thought others might want to take a look
> at the code or run their own experiments. We're expecting to post the
> individual patches soon. But, until then, the code is available here:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/vishal/tiering.git
>
> and is tagged with "tiering-0.2", aka. d8e31e81b1dca9.
>
> Note that internally folks have been calling this "hmem" which is
> terribly easy to confuse with the existing hmm. There are still some
> "hmem"'s in the tree, but I don't expect them to live much longer.
>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-10-17 8:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 20:05 [RFC] Memory Tiering Dave Hansen
2019-10-17 8:07 ` David Hildenbrand [this message]
2019-10-17 14:17 ` Dave Hansen
2019-10-17 17:07 ` Verma, Vishal L
2019-10-17 17:34 ` David Hildenbrand
2019-10-23 23:11 ` Jonathan Adams
2019-10-24 16:33 ` Dave Hansen
2019-10-25 3:30 ` Huang, Ying
2019-10-24 17:06 ` Yang Shi
2019-10-25 3:40 ` Huang, Ying
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