linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: SeongJae Park <sjpark@amazon.com>
To: SeongJae Park <sjpark@amazon.com>
Cc: <akpm@linux-foundation.org>, <Jonathan.Cameron@Huawei.com>,
	<aarcange@redhat.com>, <acme@kernel.org>,
	<alexander.shishkin@linux.intel.com>, <amit@kernel.org>,
	<benh@kernel.crashing.org>, <brendan.d.gregg@gmail.com>,
	<brendanhiggins@google.com>, <cai@lca.pw>,
	<colin.king@canonical.com>, <corbet@lwn.net>, <david@redhat.com>,
	<dwmw@amazon.com>, <elver@google.com>, <fan.du@intel.com>,
	<foersleo@amazon.de>, <gthelen@google.com>, <irogers@google.com>,
	<jolsa@redhat.com>, <kirill@shutemov.name>,
	<mark.rutland@arm.com>, <mgorman@suse.de>, <minchan@kernel.org>,
	<mingo@redhat.com>, <namhyung@kernel.org>, <peterz@infradead.org>,
	<rdunlap@infradead.org>, <riel@surriel.com>,
	<rientjes@google.com>, <rostedt@goodmis.org>, <rppt@kernel.org>,
	<sblbir@amazon.com>, <shakeelb@google.com>, <shuah@kernel.org>,
	<sj38.park@gmail.com>, <snu@amazon.de>, <vbabka@suse.cz>,
	<vdavydov.dev@gmail.com>, <yang.shi@linux.alibaba.com>,
	<ying.huang@intel.com>, <zgf574564920@gmail.com>,
	<linux-damon@amazon.com>, <linux-mm@kvack.org>,
	<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v23 03/15] mm/damon: Adaptively adjust regions
Date: Tue, 19 Jan 2021 19:36:36 +0100	[thread overview]
Message-ID: <20210119183636.327-1-sjpark@amazon.com> (raw)
In-Reply-To: <20201215115448.25633-4-sjpark@amazon.com>

On Tue, 15 Dec 2020 12:54:36 +0100 SeongJae Park <sjpark@amazon.com> wrote:

> From: SeongJae Park <sjpark@amazon.de>
> 
> Even somehow the initial monitoring target regions are well constructed
> to fulfill the assumption (pages in same region have similar access
> frequencies), the data access pattern can be dynamically changed.  This
> will result in low monitoring quality.  To keep the assumption as much
> as possible, DAMON adaptively merges and splits each region based on
> their access frequency.
> 
> For each ``aggregation interval``, it compares the access frequencies of
> adjacent regions and merges those if the frequency difference is small.
> Then, after it reports and clears the aggregated access frequency of
> each region, it splits each region into two or three regions if the
> total number of regions will not exceed the user-specified maximum
> number of regions after the split.
> 
> In this way, DAMON provides its best-effort quality and minimal overhead
> while keeping the upper-bound overhead that users set.
> 
> Signed-off-by: SeongJae Park <sjpark@amazon.de>
> Reviewed-by: Leonard Foerster <foersleo@amazon.de>
> ---
>  include/linux/damon.h |  41 +++++---
>  mm/damon/core.c       | 220 ++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 240 insertions(+), 21 deletions(-)
> 
[...]
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 167487e75737..0f9beb60d9dd 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
[...]
> +
> +/*
> + * Split a region in two
> + *
> + * r		the region to be split
> + * sz_r		size of the first sub-region that will be made
> + */
> +static void damon_split_region_at(struct damon_ctx *ctx,
> +				  struct damon_region *r, unsigned long sz_r)
> +{
> +	struct damon_region *new;
> +
> +	new = damon_new_region(r->ar.start + sz_r, r->ar.end);

Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc. found that
'damon_new_region()' could return NULL in case of memory allocation failure,
but NULL check for 'new' is missed here.  I will add the check in the next
version.

> +	r->ar.end = new->ar.start;
> +
> +	damon_insert_region(new, r, damon_next_region(r));
> +}
[...]


Thanks,
SeongJae Park



  reply	other threads:[~2021-01-19 18:37 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-15 11:54 [PATCH v23 00/15] Introduce Data Access MONitor (DAMON) SeongJae Park
2020-12-15 11:54 ` [PATCH v23 01/15] mm: " SeongJae Park
2020-12-23 15:11   ` Shakeel Butt
2020-12-23 16:33     ` SeongJae Park
2020-12-23 22:49       ` Shakeel Butt
2020-12-24  7:02         ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 02/15] mm/damon/core: Implement region-based sampling SeongJae Park
2021-02-01 17:37   ` Shakeel Butt
2021-02-02  9:17     ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 03/15] mm/damon: Adaptively adjust regions SeongJae Park
2021-01-19 18:36   ` SeongJae Park [this message]
2021-02-01 17:37   ` Shakeel Butt
2021-02-02  9:39     ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 04/15] mm/idle_page_tracking: Make PG_idle reusable SeongJae Park
2020-12-23 15:11   ` Shakeel Butt
2020-12-15 11:54 ` [PATCH v23 05/15] mm/damon: Implement primitives for the virtual memory address spaces SeongJae Park
2020-12-23 15:31   ` Shakeel Butt
2020-12-23 16:47     ` SeongJae Park
2020-12-23 22:54       ` Shakeel Butt
2020-12-24  7:11         ` SeongJae Park
2021-01-27 16:56           ` SeongJae Park
2021-01-27 17:02             ` Shakeel Butt
2020-12-15 11:54 ` [PATCH v23 06/15] mm/damon: Add a tracepoint SeongJae Park
2020-12-15 11:54 ` [PATCH v23 07/15] mm/damon: Implement a debugfs-based user space interface SeongJae Park
2021-02-01 17:37   ` Shakeel Butt
2021-02-02 10:00     ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 08/15] mm/damon/dbgfs: Implement recording feature SeongJae Park
2020-12-15 11:54 ` [PATCH v23 09/15] mm/damon/dbgfs: Export kdamond pid to the user space SeongJae Park
2020-12-15 11:54 ` [PATCH v23 10/15] mm/damon/dbgfs: Support multiple contexts SeongJae Park
2021-02-02 12:27   ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 11/15] tools: Introduce a minimal user-space tool for DAMON SeongJae Park
2020-12-23 18:37   ` SeongJae Park
2020-12-23 22:56     ` Shakeel Butt
2020-12-24  7:13       ` SeongJae Park
2020-12-15 11:54 ` [PATCH v23 12/15] Documentation: Add documents " SeongJae Park
2020-12-15 11:54 ` [PATCH v23 13/15] mm/damon: Add kunit tests SeongJae Park
2020-12-15 11:54 ` [PATCH v23 14/15] mm/damon: Add user space selftests SeongJae Park
2020-12-15 11:54 ` [PATCH v23 15/15] MAINTAINERS: Update for DAMON SeongJae Park

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210119183636.327-1-sjpark@amazon.com \
    --to=sjpark@amazon.com \
    --cc=Jonathan.Cameron@Huawei.com \
    --cc=aarcange@redhat.com \
    --cc=acme@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=amit@kernel.org \
    --cc=benh@kernel.crashing.org \
    --cc=brendan.d.gregg@gmail.com \
    --cc=brendanhiggins@google.com \
    --cc=cai@lca.pw \
    --cc=colin.king@canonical.com \
    --cc=corbet@lwn.net \
    --cc=david@redhat.com \
    --cc=dwmw@amazon.com \
    --cc=elver@google.com \
    --cc=fan.du@intel.com \
    --cc=foersleo@amazon.de \
    --cc=gthelen@google.com \
    --cc=irogers@google.com \
    --cc=jolsa@redhat.com \
    --cc=kirill@shutemov.name \
    --cc=linux-damon@amazon.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mark.rutland@arm.com \
    --cc=mgorman@suse.de \
    --cc=minchan@kernel.org \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rdunlap@infradead.org \
    --cc=riel@surriel.com \
    --cc=rientjes@google.com \
    --cc=rostedt@goodmis.org \
    --cc=rppt@kernel.org \
    --cc=sblbir@amazon.com \
    --cc=shakeelb@google.com \
    --cc=shuah@kernel.org \
    --cc=sj38.park@gmail.com \
    --cc=snu@amazon.de \
    --cc=vbabka@suse.cz \
    --cc=vdavydov.dev@gmail.com \
    --cc=yang.shi@linux.alibaba.com \
    --cc=ying.huang@intel.com \
    --cc=zgf574564920@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).