From: <sieberf@amazon.com>
To: <sj38.park@gmail.com>
Cc: <Jonathan.Cameron@Huawei.com>, <acme@kernel.org>,
<akpm@linux-foundation.org>, <alexander.shishkin@linux.intel.com>,
<amit@kernel.org>, <benh@kernel.crashing.org>,
<brendanhiggins@google.com>, <corbet@lwn.net>, <david@redhat.com>,
<dwmw@amazon.com>, <elver@google.com>, <fan.du@intel.com>,
<foersleo@amazon.de>, <greg@kroah.com>, <gthelen@google.com>,
<guoju.fgj@alibaba-inc.com>, <linux-damon@amazon.com>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-mm@kvack.org>, <mgorman@suse.de>, <minchan@kernel.org>,
<mingo@redhat.com>, <namhyung@kernel.org>, <peterz@infradead.org>,
<riel@surriel.com>, <rientjes@google.com>, <rostedt@goodmis.org>,
<rppt@kernel.org>, <shakeelb@google.com>, <shuah@kernel.org>,
<sjpark@amazon.de>, <snu@amazon.de>, <vbabka@suse.cz>,
<vdavydov.dev@gmail.com>, <zgf574564920@gmail.com>
Subject: Re: [PATCH v29 03/13] mm/damon: Adaptively adjust regions
Date: Tue, 25 May 2021 17:17:05 +0200 [thread overview]
Message-ID: <1b30265d-7440-1c94-f625-0087215433ee@amazon.com> (raw)
In-Reply-To: <20210520075629.4332-4-sj38.park@gmail.com>
Hi SeongJae,
The code looks good. Some questions for this patch:
The region merge threshold is computed on the access diff. Should the
diff threshold be exponential as diffs in low number of access are
likely to be more important? I.e if the threshold is 5, a region A with
0 accesses will be merged with a region B with 4 accesses (diff=4), but
a region C with 50 access won't be merged with a region D with 60
accesses (diff=10), however it seems to me that keeping a good
granularity between A and B is more important than between C and D for
FPR. What do you think?
When the number of regions is less than half max region, region split
kicks in and doubles the number of region. This means that the number of
region will grow close to max region, then slowly decay as region
merges, until it reaches half max regions, then double again. This seems
to create a non-uniform region number distribution over time, with large
cycles. Also we do a lot of work when we double and no work otherwise.
Not sure what's the impact on measurement quality but intuitively seems
like keeping the number of regions constant over time would yield more
consistent metrics? How about we rather always split regions at each
iteration, and for each region we give a split probability?
Kind regards,
--Fernand
next prev parent reply other threads:[~2021-05-25 15:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 7:56 [PATCH v29 00/13] Introduce Data Access MONitor (DAMON) SeongJae Park
2021-05-20 7:56 ` [PATCH v29 01/13] mm: " SeongJae Park
2021-05-20 7:56 ` [PATCH v29 02/13] mm/damon/core: Implement region-based sampling SeongJae Park
2021-05-20 7:56 ` [PATCH v29 03/13] mm/damon: Adaptively adjust regions SeongJae Park
2021-05-25 15:17 ` sieberf [this message]
2021-05-25 15:39 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 04/13] mm/idle_page_tracking: Make PG_idle reusable SeongJae Park
2021-06-11 12:55 ` Shah, Amit
2021-06-11 13:49 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 05/13] mm/damon: Implement primitives for the virtual memory address spaces SeongJae Park
2021-05-25 15:19 ` sieberf
2021-05-25 15:44 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 06/13] mm/damon: Add a tracepoint SeongJae Park
2021-05-20 7:56 ` [PATCH v29 07/13] mm/damon: Implement a debugfs-based user space interface SeongJae Park
2021-06-11 18:59 ` sieberf
2021-06-14 6:48 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 08/13] mm/damon/dbgfs: Export kdamond pid to the user space SeongJae Park
2021-05-20 7:56 ` [PATCH v29 09/13] mm/damon/dbgfs: Support multiple contexts SeongJae Park
2021-06-14 9:30 ` sieberf
2021-06-14 9:35 ` SeongJae Park
2021-06-14 9:44 ` Greg KH
2021-05-20 7:56 ` [PATCH v29 10/13] Documentation: Add documents for DAMON SeongJae Park
2021-06-09 7:03 ` SeongJae Park
2021-06-11 17:44 ` Boehme, Markus
2021-06-11 18:53 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 11/13] mm/damon: Add kunit tests SeongJae Park
2021-05-20 7:56 ` [PATCH v29 12/13] mm/damon: Add user space selftests SeongJae Park
2021-06-11 13:57 ` Maximilian Heyne
2021-06-11 14:04 ` SeongJae Park
2021-05-20 7:56 ` [PATCH v29 13/13] MAINTAINERS: Update for DAMON SeongJae Park
2021-05-20 22:34 ` [PATCH v29 00/13] Introduce Data Access MONitor (DAMON) Andrew Morton
2021-05-21 2:53 ` Shakeel Butt
2021-05-21 8:55 ` Shah, Amit
2021-06-14 8:09 ` sieberf
2021-06-15 16:30 ` sieberf
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