From: "ying.huang@intel.com" <ying.huang@intel.com>
To: Wei Xu <weixugc@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Thelen <gthelen@google.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.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: Fri, 13 May 2022 11:25:34 +0800 [thread overview]
Message-ID: <69f2d063a15f8c4afb4688af7b7890f32af55391.camel@intel.com> (raw)
In-Reply-To: <CAAPL-u-DGLcKRVDnChN9ZhxPkfxQvz9Sb93kVoX_4J2oiJSkUw@mail.gmail.com>
On Wed, 2022-05-11 at 23:22 -0700, Wei Xu wrote:
>
> Memory Allocation for Demotion
> ==============================
>
> To allocate a new page as the demotion target for a page, the kernel
> calls the allocation function (__alloc_pages_nodemask) with the
> source page node as the preferred node and the union of all lower
> tier nodes as the allowed nodemask. The actual target node selection
> then follows the allocation fallback order that the kernel has
> already defined.
>
> The pseudo code looks like:
>
> targets = NODE_MASK_NONE;
> src_nid = page_to_nid(page);
> src_tier = node_tier_map[src_nid];
> for (i = src_tier + 1; i < MAX_MEMORY_TIERS; i++)
> nodes_or(targets, targets, memory_tiers[i]);
> new_page = __alloc_pages_nodemask(gfp, order, src_nid, targets);
>
> The memopolicy of cpuset, vma and owner task of the source page can
> be set to refine the demotion target nodemask, e.g. to prevent
> demotion or select a particular allowed node as the demotion target.
Consider a system with 3 tiers, if we want to demote some pages from
tier 0, the desired behavior is,
- Allocate pages from tier 1
- If there's no enough free pages in tier 1, wakeup kswapd of tier 1 so
demote some pages from tier 1 to tier 2
- If there's still no enough free pages in tier 1, allocate pages from
tier 2.
In this way, tier 0 will have the hottest pages, while tier 1 will have
the coldest pages.
With your proposed method, the demoting from tier 0 behavior is,
- Allocate pages from tier 1
- If there's no enough free pages in tier 1, allocate pages in tier 2
The kswapd of tier 1 will not be waken up until there's no enough free
pages in tier 2. In quite long time, there's no much hot/cold
differentiation between tier 1 and tier 2.
This isn't hard to be fixed, just call __alloc_pages_nodemask() for each
tier one by one considering page allocation fallback order.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2022-05-13 3:25 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
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 [this message]
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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