From: Michal Hocko <mhocko@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
dan.j.williams@intel.com
Subject: Re: [PATCH 0/4] [RFC] Migrate Pages in lieu of discard
Date: Tue, 22 Oct 2019 15:49:50 +0200 [thread overview]
Message-ID: <20191022134950.GQ9379@dhcp22.suse.cz> (raw)
In-Reply-To: <0b05c135-4762-e745-5289-58ee84cc8c3e@intel.com>
On Fri 18-10-19 07:54:20, Dave Hansen wrote:
> On 10/18/19 12:44 AM, Michal Hocko wrote:
> > How does this compare to
> > http://lkml.kernel.org/r/1560468577-101178-1-git-send-email-yang.shi@linux.alibaba.com
>
> It's a _bit_ more tied to persistent memory and it appears a bit more
> tied to two tiers rather something arbitrarily deep. They're pretty
> similar conceptually although there are quite a few differences.
>
> For instance, what I posted has a static mapping for the migration path.
> If node A is in reclaim, we always try to allocate pages on node B.
> There are no restrictions on what those nodes can be. In Yang Shi's
> apporach, there's a dynamic search for a target migration node on each
> migration that follows the normal alloc fallback path. This ends up
> making migration nodes special.
As we have discussed at LSFMM this year and there seemed to be a goog
consensus on that, the resulting implementation should be as pmem
neutral as possible. After all node migration mode sounds like a
reasonable feature even without pmem. So I would be more inclined to the
normal alloc fallback path rather than a very specific and static
migration fallback path. If that turns out impractical then sure let's
come up with something more specific but I think there is quite a long
route there because we do not really have much of an experience with
this so far.
> There are also some different choices that are pretty arbitrary. For
> instance, when you allocation a migration target page, should you cause
> memory pressure on the target?
Those are details to really sort out and they require some
experimentation to.
> To be honest, though, I don't see anything fatally flawed with it. It's
> probably a useful exercise to factor out the common bits from the two
> sets and see what we can agree on being absolutely necessary.
Makes sense. What would that be? Is there a real consensus on having the
new node_reclaim mode to be the configuration mechanism? Do we want to
support generic NUMA without any PMEM in place as well for starter?
Thanks!
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2019-10-22 13:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 22:11 Dave Hansen
2019-10-16 22:11 ` [PATCH 1/4] node: Define and export memory migration path Dave Hansen
2019-10-17 11:12 ` Kirill A. Shutemov
2019-10-17 11:44 ` Kirill A. Shutemov
2019-10-16 22:11 ` [PATCH 2/4] mm/migrate: Defer allocating new page until needed Dave Hansen
2019-10-17 11:27 ` Kirill A. Shutemov
2019-10-16 22:11 ` [PATCH 3/4] mm/vmscan: Attempt to migrate page in lieu of discard Dave Hansen
2019-10-17 17:30 ` Yang Shi
2019-10-18 18:15 ` Dave Hansen
2019-10-18 21:02 ` Yang Shi
2019-10-16 22:11 ` [PATCH 4/4] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2019-10-17 3:45 ` [PATCH 0/4] [RFC] Migrate Pages in lieu of discard Shakeel Butt
2019-10-17 14:26 ` Dave Hansen
2019-10-17 16:58 ` Shakeel Butt
2019-10-17 20:51 ` Dave Hansen
2019-10-17 17:20 ` Yang Shi
2019-10-17 21:05 ` Dave Hansen
2019-10-17 22:58 ` Shakeel Butt
2019-10-18 21:44 ` Yang Shi
2019-10-17 16:01 ` Suleiman Souhlal
2019-10-17 16:32 ` Dave Hansen
2019-10-17 16:39 ` Shakeel Butt
2019-10-18 8:11 ` Suleiman Souhlal
2019-10-18 15:10 ` Dave Hansen
2019-10-18 15:39 ` Suleiman Souhlal
2019-10-18 7:44 ` Michal Hocko
2019-10-18 14:54 ` Dave Hansen
2019-10-18 21:39 ` Yang Shi
2019-10-18 21:55 ` Dan Williams
2019-10-22 13:49 ` Michal Hocko [this message]
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