Re: [Patch] ipc: HARD_MSGMAX should be higher not lower on 64bit

Serge E. Hallyn
2009-12-11T16:11:29Z

Quoting Américo Wang (xiyou.wangcong@gmail.com):
>
> (Hi, I am the same person.)
>
> On Fri, Dec 11, 2009 at 08:44:33AM -0600, Serge E. Hallyn wrote:
> >Quoting Amerigo Wang (amwang@redhat.com):
> >> It looks weird that we have HARD_MSGMAX lower on 64bit than on 32bit,
> >> since usually 64bit machines have more memory than 32bit machines.
> >
> >It does look like this may have been an accident.
> >
>
> OK.
>
> >> Making it higher on 64bit seems reasonable, and keep the original
> >> number on 32bit.
> >>
> >> Cc: Serge E. Hallyn <serue@us.ibm.com>
> >> Cc: Cedric Le Goater <clg@fr.ibm.com>
> >> Signed-off-by: WANG Cong <amwang@redhat.com>
> >>
> >> ---
> >> diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
> >> index e408722..07baa38 100644
> >> --- a/include/linux/ipc_namespace.h
> >> +++ b/include/linux/ipc_namespace.h
> >> @@ -87,7 +87,7 @@ extern int mq_init_ns(struct ipc_namespace *ns);
> >> /* default values */
> >> #define DFLT_QUEUESMAX 256 /* max number of message queues */
> >> #define DFLT_MSGMAX 10 /* max number of messages in each queue */
> >> -#define HARD_MSGMAX (131072/sizeof(void *))
> >> +#define HARD_MSGMAX (32768*sizeof(void *)/4)
> >
> >why /4 ? You're now making it much smaller for 32-bit than it
> >used to be?
> >
>
> Yes?
>
> Before this patch, it is 131072/sizeof(void*) = 32768;
> after this patch, it is 32768*sizeof(void*)/4 = 32768 too.
> Both on 32bit, of course.
>
> Am I missing something?

Haha, nope.

Acked-by: Serge Hallyn <serue@us.ibm.com>

thanks,
-serge