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

Américo Wang
2009-12-11T15:20:11Z

(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?

--
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