From: "Luis R. Rodriguez" <mcgrof@suse.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>,
gregkh@linuxfoundation.org, hpa@linux.intel.com,
linux-kernel@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
Stephen Warren <swarren@wwwdotorg.org>,
Michal Hocko <mhocko@suse.cz>, Petr Mladek <pmladek@suse.cz>,
Joe Perches <joe@perches.com>, Arun KS <arunks.linux@gmail.com>,
Kees Cook <keescook@chromium.org>,
Davidlohr Bueso <davidlohr@hp.com>,
Chris Metcalf <cmetcalf@tilera.com>
Subject: Re: [PATCH v8 4/4] printk: allow increasing the ring buffer depending on the number of CPUs
Date: Tue, 24 Jun 2014 02:20:50 +0200 [thread overview]
Message-ID: <20140624002050.GC27687@wotan.suse.de> (raw)
In-Reply-To: <20140623154134.43ac7ab63896cd9ebcba84b6@linux-foundation.org>
On Mon, Jun 23, 2014 at 03:41:34PM -0700, Andrew Morton wrote:
> On Wed, 18 Jun 2014 13:45:37 -0700 "Luis R. Rodriguez" <mcgrof@do-not-panic.com> wrote:
>
> > ...
> >
> > If an increase is required the ring buffer is increased to
> > + the next power of 2 that can fit both the minimum kernel ring buffer
> > + (LOG_BUF_SHIFT) plus the additional worst case CPU contributions.
> >
> > ...
> >
> > + log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
> > +}
>
> I'd have expected
>
> total_cpu_space = minimum-per-cpu-len * nr_possible_cpus;
> log_buf_len = max(__LOG_BUF_LEN, total_cpu_space)
>
> but here you added __LOG_BUF_LEN to total_cpu_space and I cannot work
> out why.
> .
Ah, because its cpu_extra, not total_cpu_space that is being
computed, the goal was to see how much extra junk on the
worst case a CPU might contribute. The __LOG_BUF_LEN is the
default size, so we combine both.
Luis
next prev parent reply other threads:[~2014-06-24 0:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-18 20:45 [PATCH v8 1/4] printk: make dynamic kernel ring buffer alignment explicit Luis R. Rodriguez
2014-06-18 20:45 ` [PATCH v8 2/4] printk: move power of 2 practice of ring buffer size to a helper Luis R. Rodriguez
2014-06-18 20:45 ` [PATCH v8 3/4] printk: make dynamic units clear for the kernel ring buffer Luis R. Rodriguez
2014-06-18 20:45 ` [PATCH v8 4/4] printk: allow increasing the ring buffer depending on the number of CPUs Luis R. Rodriguez
2014-06-23 22:41 ` Andrew Morton
2014-06-24 0:20 ` Luis R. Rodriguez [this message]
2014-06-24 0:45 ` Andrew Morton
2014-06-24 1:05 ` Luis R. Rodriguez
2014-06-26 21:41 ` Andrew Morton
2014-06-26 23:16 ` Luis R. Rodriguez
2014-06-26 23:20 ` Andrew Morton
2014-06-26 23:32 ` Luis R. Rodriguez
2014-06-27 23:59 ` Andrew Morton
2014-06-28 1:20 ` Luis R. Rodriguez
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=20140624002050.GC27687@wotan.suse.de \
--to=mcgrof@suse.com \
--cc=akpm@linux-foundation.org \
--cc=andrew@lunn.ch \
--cc=arunks.linux@gmail.com \
--cc=cmetcalf@tilera.com \
--cc=davidlohr@hp.com \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@linux.intel.com \
--cc=joe@perches.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mcgrof@do-not-panic.com \
--cc=mhocko@suse.cz \
--cc=pmladek@suse.cz \
--cc=swarren@wwwdotorg.org \
/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).