From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
Tzvetomir Stoyanov <tz.stoyanov@gmail.com>,
Vincent Donnefort <vdonnefort@google.com>,
Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: [PATCH v5 04/15] ring-buffer: Set new size of the ring buffer sub page
Date: Thu, 21 Dec 2023 09:11:01 +0900 [thread overview]
Message-ID: <20231221091101.c518d74654d507af07c53eb1@kernel.org> (raw)
In-Reply-To: <20231220115602.1903bf77@gandalf.local.home>
On Wed, 20 Dec 2023 11:56:02 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 21 Dec 2023 01:34:56 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
>
> > On Tue, 19 Dec 2023 13:54:18 -0500
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > > From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
> > >
> > > There are two approaches when changing the size of the ring buffer
> > > sub page:
> > > 1. Destroying all pages and allocating new pages with the new size.
> > > 2. Allocating new pages, copying the content of the old pages before
> > > destroying them.
> > > The first approach is easier, it is selected in the proposed
> > > implementation. Changing the ring buffer sub page size is supposed to
> > > not happen frequently. Usually, that size should be set only once,
> > > when the buffer is not in use yet and is supposed to be empty.
> > >
> > > Link: https://lore.kernel.org/linux-trace-devel/20211213094825.61876-5-tz.stoyanov@gmail.com
> > >
> >
> > OK, this actually reallocate the sub buffers when a new order is set.
> > BTW, with this change, if we set a new order, the total buffer size will be
> > changed too? Or reserve the total size? I think either is OK but it should
> > be described in the document. (e.g. if it is changed, user should set the
> > order first and set the total size later.)
> >
>
> Patch 11 keeps the same size of the buffer. As I would think that would be
> what the user would expect. And not only that, it breaks the latency
> tracers if it doesn't keep the same size.
Got it!
Thanks!
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
next prev parent reply other threads:[~2023-12-21 0:11 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-19 18:54 [PATCH v5 00/15] ring-buffer/tracing: Allow ring buffer to have bigger sub buffers Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 01/15] ring-buffer: Refactor ring buffer implementation Steven Rostedt
2023-12-20 9:48 ` Masami Hiramatsu
2023-12-20 12:53 ` Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 02/15] ring-buffer: Page size per ring buffer Steven Rostedt
2023-12-20 8:48 ` David Laight
2023-12-20 13:01 ` Steven Rostedt
2023-12-21 9:17 ` David Laight
2023-12-21 14:19 ` Steven Rostedt
2023-12-21 14:51 ` David Laight
2023-12-21 14:57 ` Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 03/15] ring-buffer: Add interface for configuring trace sub buffer size Steven Rostedt
2023-12-20 14:26 ` Masami Hiramatsu
2023-12-20 14:40 ` Steven Rostedt
2023-12-21 0:10 ` Masami Hiramatsu
2023-12-19 18:54 ` [PATCH v5 04/15] ring-buffer: Set new size of the ring buffer sub page Steven Rostedt
2023-12-20 16:34 ` Masami Hiramatsu
2023-12-20 16:56 ` Steven Rostedt
2023-12-21 0:11 ` Masami Hiramatsu [this message]
2023-12-19 18:54 ` [PATCH v5 05/15] ring-buffer: Read and write to ring buffers with custom sub buffer size Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 06/15] ring-buffer: Clear pages on error in ring_buffer_subbuf_order_set() failure Steven Rostedt
2023-12-20 16:23 ` Masami Hiramatsu
2023-12-20 16:30 ` Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 07/15] ring-buffer: Do no swap cpu buffers if order is different Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 08/15] ring-buffer: Make sure the spare sub buffer used for reads has same size Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 09/15] tracing: Update snapshot order along with main buffer order Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 10/15] tracing: Stop the tracing while changing the ring buffer subbuf size Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 11/15] ring-buffer: Keep the same size when updating the order Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 12/15] ring-buffer: Just update the subbuffers when changing their allocation order Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 13/15] ring-buffer: Add documentation on the buffer_subbuf_order file Steven Rostedt
2023-12-19 18:54 ` [PATCH v5 14/15] ringbuffer/selftest: Add basic selftest to test changing subbuf order Steven Rostedt
2023-12-21 0:23 ` Masami Hiramatsu
2023-12-19 18:54 ` [PATCH v5 15/15] tracing: Update subbuffer with kilobytes not page order Steven Rostedt
2023-12-21 0:26 ` Masami Hiramatsu
2023-12-21 1:57 ` Steven Rostedt
2023-12-19 22:38 ` [PATCH v5 16/15] ring-buffer: Use subbuf_order for buffer page masking Steven Rostedt
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=20231221091101.c518d74654d507af07c53eb1@kernel.org \
--to=mhiramat@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=kent.overstreet@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=rostedt@goodmis.org \
--cc=tz.stoyanov@gmail.com \
--cc=vdonnefort@google.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
all inboxes | Powered by JetHome®