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From: Rik van Riel <riel@surriel.com>
To: Michal Hocko <mhocko@suse.com>, David Hildenbrand <david@redhat.com>
Cc: Stefan Roesch <shr@devkernel.io>,
	linux-mm@kvack.org, linux-doc@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, CGEL <cgel.zte@gmail.com>,
	Jann Horn <jannh@google.com>
Subject: Re: [RESEND RFC PATCH v1 00/20] mm: process/cgroup ksm support
Date: Wed, 25 Jan 2023 13:43:09 -0500	[thread overview]
Message-ID: <4fe0e2eb6a3e2d7e0838f177706f1be13d61375c.camel@surriel.com> (raw)
In-Reply-To: <Y9EoJ0jlXMeuJzuY@dhcp22.suse.cz>

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On Wed, 2023-01-25 at 14:01 +0100, Michal Hocko wrote:
> 
> I have read through your cover letter and it talks about the
> interface
> but it doesn't really talk about usecases and how they are supposed
> to
> use this feature - except the prctl based flag gets inherited. So
> could
> you elaborate some more about those usecases please?

I can explain a little about the use case. There are people
who use forked (rather than threaded) servers for certain
workloads, from a garbage collected language without pointers,
which means madvise simply cannot be made available in that
language.

The people running that workload have experimented with uKSM
in the past, and seen about a 20% capacity increase from
doing that.

Because madvise is not possible in that programming language,
and the addresses of data keep moving around as things get
garbage collected, KSM sharing needs to be enabled "from the
outside" for that workload.

prctl seems like a good way to do that.

-- 
All Rights Reversed.

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      reply	other threads:[~2023-01-25 19:18 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-23 17:37 [RESEND RFC PATCH v1 00/20] mm: process/cgroup ksm support Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 01/20] mm: add new flag to enable ksm per process Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 02/20] mm: add flag to __ksm_enter Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 03/20] mm: add flag to __ksm_exit call Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 04/20] mm: invoke madvise for all vmas in scan_get_next_rmap_item Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 05/20] mm: support disabling of ksm for a process Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 06/20] mm: add new prctl option to get and set " Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 07/20] mm: add tracepoints to ksm Stefan Roesch
2023-01-30 17:03   ` Steven Rostedt
2023-01-23 17:37 ` [RESEND RFC PATCH v1 08/20] mm: split off pages_volatile function Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 09/20] mm: expose general_profit metric Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 10/20] docs: document general_profit sysfs knob Stefan Roesch
2023-01-24  4:07   ` Bagas Sanjaya
2023-01-24 16:21     ` Jonathan Corbet
2023-01-26  2:31       ` Bagas Sanjaya
2023-01-23 17:37 ` [RESEND RFC PATCH v1 11/20] mm: calculate ksm process profit metric Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 12/20] mm: add ksm_merge_type() function Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 13/20] mm: expose ksm process profit metric in ksm_stat Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 14/20] mm: expose ksm merge type " Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 15/20] docs: document new procfs ksm knobs Stefan Roesch
2023-01-24  4:09   ` Bagas Sanjaya
2023-01-23 17:37 ` [RESEND RFC PATCH v1 16/20] tools: add new prctl flags to prctl in tools dir Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 17/20] selftests/vm: add KSM prctl merge test Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 18/20] selftests/vm: add KSM get merge type test Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 19/20] selftests/vm: add KSM fork test Stefan Roesch
2023-01-23 17:37 ` [RESEND RFC PATCH v1 20/20] selftests/vm: add two functions for debugging merge outcome Stefan Roesch
2023-01-24 16:38 ` [RESEND RFC PATCH v1 00/20] mm: process/cgroup ksm support David Hildenbrand
2023-01-24 17:37   ` Stefan Roesch
2023-01-24 18:01     ` David Hildenbrand
2023-01-25 13:01       ` Michal Hocko
2023-01-25 18:43         ` Rik van Riel [this message]

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