From: SJ Park <sj@kernel.org>
To: pratmal@google.com
Cc: SJ Park <sj@kernel.org>,
akpm@linux-foundation.org, vbabka@kernel.org, david@kernel.org,
corbet@lwn.net, skhan@linuxfoundation.org,
anshuman.khandual@arm.com, gthelen@google.com, surenb@google.com,
mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org,
ziy@nvidia.com, ljs@kernel.org, liam@infradead.org,
rppt@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v3] mm/page_reporting: Add page_reporting_delay_ms module parameter
Date: Mon, 27 Jul 2026 16:59:25 -0700 [thread overview]
Message-ID: <20260727235925.93406-1-sj@kernel.org> (raw)
In-Reply-To: <20260727230545.262579-1-pratmal@google.com>
On Mon, 27 Jul 2026 23:05:45 +0000 pratmal@google.com wrote:
> From: Pratyush Mallick <pratmal@google.com>
>
> Currently, the free page reporting uses a hardcoded delay of
> (2 HZ) between reporting intervals. While this is a reasonable
> default, it lacks the flexibility to adapt to varying guest workloads.
>
> A low delay allows aggressive memory reclamation, returning unused
> pages to the host as quickly as possible. However, during spiky
> allocation/free churn, this immediate reporting can lead to a severe
> performance penalty (nested page faults) as the guest re-allocates memory
> that the host has just unmapped. In these scenarios, there is benefit
> from increasing the delay to batch free pages over a longer window,
> absorbing the churn without hypercall and re-fault overhead.
>
> This patch exposes the delay as a module parameter:
> /sys/module/page_reporting/parameters/page_reporting_delay_ms, measured
> in milliseconds and defaults to 2000ms.
Makes sense to me.
>
> Signed-off-by: Pratyush Mallick <pratmal@google.com>
Reviewed-by: SJ Park <sj@kernel.org>
Thanks,
SJ
[...]
next prev parent reply other threads:[~2026-07-27 23:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-27 23:05 [PATCH v3] mm/page_reporting: Add page_reporting_delay_ms module parameter pratmal
2026-07-27 23:59 ` SJ Park [this message]
2026-07-28 1:13 ` Andrew Morton
2026-07-28 4:17 ` Pratyush Mallick
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