From: Andrew Morton <akpm@linux-foundation.org>
To: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>, Chris Mason <clm@fb.com>,
Kiryl Shutsemau <kirill@shutemov.name>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Brendan Jackman <jackmanb@google.com>,
David Hildenbrand <david@redhat.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Michal Hocko <mhocko@suse.com>, Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Vlastimil Babka <vbabka@suse.cz>, Zi Yan <ziy@nvidia.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kernel-team@meta.com
Subject: Re: [PATCH 0/4] mm/page_alloc: Batch callers of free_pcppages_bulk
Date: Fri, 19 Sep 2025 13:06:44 -0700 [thread overview]
Message-ID: <20250919130644.f3a4afdf0c2e51bbec59b6e0@linux-foundation.org> (raw)
In-Reply-To: <20250919195223.1560636-1-joshua.hahnjy@gmail.com>
On Fri, 19 Sep 2025 12:52:18 -0700 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:
> While testing workloads with high sustained memory pressure on large machines
> (1TB memory, 316 CPUs), we saw an unexpectedly high number of softlockups.
> Further investigation showed that the lock in free_pcppages_bulk was being held
> for a long time, even being held while 2k+ pages were being freed [1].
What problems are caused by this, apart from a warning which can
presumably be suppressed in some fashion?
> This causes starvation in other processes for both the pcp and zone locks,
> which can lead to softlockups that cause the system to stall [2].
[2] doesn't describe such stalls.
>
> ...
>
> In our fleet, we have seen that performing batched lock freeing has led to
> significantly lower rates of softlockups, while incurring relatively small
> regressions (relative to the workload and relative to the variation).
"our" == Meta?
next prev parent reply other threads:[~2025-09-19 20:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-19 19:52 Joshua Hahn
2025-09-19 19:52 ` [PATCH 1/4] mm/page_alloc/vmstat: Simplify refresh_cpu_vm_stats change detection Joshua Hahn
2025-09-19 19:52 ` [PATCH 2/4] mm/page_alloc: Perform appropriate batching in drain_pages_zone Joshua Hahn
2025-09-19 19:52 ` [PATCH 3/4] mm/page_alloc: Batch page freeing in decay_pcp_high Joshua Hahn
2025-09-19 19:52 ` [PATCH 4/4] mm/page_alloc: Batch page freeing in free_frozen_page_commit Joshua Hahn
2025-09-20 14:41 ` kernel test robot
2025-09-20 17:12 ` kernel test robot
2025-09-19 20:06 ` Andrew Morton [this message]
2025-09-19 21:06 ` [PATCH 0/4] mm/page_alloc: Batch callers of free_pcppages_bulk Joshua Hahn
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