Query about cyclic buffer size

Atsushi Kumagai kumagai-atsushi at mxc.nes.nec.co.jp
Tue Oct 2 00:55:17 EDT 2012

Hello Vivek,

On Thu, 20 Sep 2012 09:12:41 -0400
Vivek Goyal <vgoyal at redhat.com> wrote:
> > Now, I think makedumpfile should automatically choose the lesser of the two below
> > as the size of cyclic buffer when the size isn't specified:
> > 
> >   a. the size enough for storing the 1st/2nd bitmap for the whole of vmcore
> >   b. the limit size (e.g. 70-80% of free memory)
> > 
> > However, I don't have a good idea how to determine the appropriate size
> > for the case of "b". 
> > If someone have a idea for the limit size, please let me know.
> May be just look at "free" output or "cat /proc/meminfo" and grep for
> "MemFree" calculate the size of buffer.

Thank you for your answer, but what I minded was to allocate most of 
free memory is safe or not.
But now, I think it may be safe because processes which need some memory
will not be created while makedumpfile is running.

So, I will try to implement the above idea for v1.5.1.
When I make the patch, I will post them.

Atsushi Kumagai

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