linux-kernel - Re: [PATCH] tracing: document buffer_size

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Message-ID: <20231002110935.2fde6637@gandalf.local.home>
Date:   Mon, 2 Oct 2023 11:09:35 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Christian Loehle <christian.loehle@....com>
Cc:     Zheng Yejian <zhengyejian1@...wei.com>, mhiramat@...nel.org,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH] tracing: document buffer_size_kb more precisely

On Tue, 26 Sep 2023 11:38:14 +0100
Christian Loehle <christian.loehle@....com> wrote:

> >> @@ -191,7 +191,7 @@ of ftrace. Here is a list of some of the key files:
> >>       A few extra pages may be allocated to accommodate buffer management
> >>       meta-data. If the last page allocated has room for more bytes
> >>       than requested, the rest of the page will be used,
> >> -    making the actual allocation bigger than requested or shown.
> >> +    making the actual allocation bigger than requested.  
> > 
> > Hi, the actual allocation should still be bigger than shown due to the
> > loss of accuracy when doing unit conversion from bytes to kilobytes (see
> > tracing_entries_read()).
> >   
> Right, the sysfs obviously only allows for KB aligned setting, but you're right.
> If set on the cmdline non-KB multiples are possible and accuracy is lost.
> Nevermind then.

I'm assuming this patch can be dropped?

-- Steve