From: Vlastimil Babka <vbabka@suse.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
Michal Hocko <mhocko@suse.com>, Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andrea Arcangeli <aarcange@redhat.com>,
Linux-MM <linux-mm@kvack.org>,
mm-commits@vger.kernel.org
Subject: Re: [patch 01/11] mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations
Date: Tue, 14 Jan 2020 09:05:57 +0100 [thread overview]
Message-ID: <90d8ba5d-9462-bcfa-3e93-2ca53f1010ba@suse.cz> (raw)
In-Reply-To: <CAHk-=whckmydNN7Ph1ihnA_tycQcc6XaRO2hikvYzyL8ZoMwOQ@mail.gmail.com>
On 1/14/20 3:16 AM, Linus Torvalds wrote:
> On Mon, Jan 13, 2020 at 4:29 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>>
>> From: Vlastimil Babka <vbabka@suse.cz>
>> Subject: mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations
>
> I absolutely _detest_ how we've had this pattern of trying to change
> the THP logic in a late -rc game.
>
> Considering how unsuccessful some of the earlier attempts have been,
> late -rc kernels really are *not* the time to make changes like this.
Agreed, myself would have been much more comfortable in rc1.
> I'm going to take it this time, but
Thanks.
> (a) I'm going to revert *immediately* if anybody even peeps about the
> new behavior
>
> (b) I want this to stop. Andrew - send THP "tweaks" during the merge
> window, and not like some late-rc "fixes", when there are absolutely
> _zero_ performance numbers or anything else critical associated with
> the patch.
>
> IOW, there is a decided lack of "bugfix" here. And if there actually
> _were_ performance numbers, they should have been in the explanation.
FWIW Mel did some tests [1] which showed some improvement to THP success rate
and no significant extra swapping that was feared. We didn't get confirmation
from Andrea about his real life workloads though.
[1] https://lore.kernel.org/linux-mm/20191113112042.GG28938@suse.de/
> So stop randomly messing with the THP allocation code, since it's
> _known_ to be fragile with subtle side effects.
>
> Linus
>
next prev parent reply other threads:[~2020-01-14 8:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 0:28 incoming Andrew Morton
2020-01-14 0:29 ` [patch 01/11] mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations Andrew Morton
2020-01-14 2:16 ` Linus Torvalds
2020-01-14 8:05 ` Vlastimil Babka [this message]
2020-01-14 8:46 ` Michal Hocko
2020-01-14 0:29 ` [patch 02/11] mm/memory_hotplug: don't free usage map when removing a re-added early section Andrew Morton
2020-01-14 0:29 ` [patch 03/11] mm/huge_memory.c: thp: fix conflict of above-47bit hint address and PMD alignment Andrew Morton
2020-01-14 0:29 ` [patch 04/11] mm/shmem.c: thp, shmem: " Andrew Morton
2020-01-14 0:29 ` [patch 05/11] mm: memcg/slab: fix percpu slab vmstats flushing Andrew Morton
2020-01-14 0:29 ` [patch 06/11] mm, debug_pagealloc: don't rely on static keys too early Andrew Morton
2020-01-14 0:29 ` [patch 07/11] mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() Andrew Morton
2020-01-14 0:29 ` [patch 08/11] mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide Andrew Morton
2020-01-14 0:29 ` [patch 09/11] mm/page-writeback.c: improve arithmetic divisions Andrew Morton
2020-01-14 0:29 ` [patch 10/11] mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid Andrew Morton
2020-01-14 0:29 ` [patch 11/11] mm: khugepaged: add trace status description for SCAN_PAGE_HAS_PRIVATE Andrew Morton
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