Re: Virtual memory consumption (both user and kernel) in modern CURRENT

From: Dmitry Pryanishnikov <dmitry_at_atlantis.dp.ua>
Date: Thu, 16 Feb 2006 14:15:55 +0200 (EET)
Hello!

On Wed, 15 Feb 2006, David Xu wrote:
>> 1) Is it normal that virtual memory size for almost every non-kernel 
>> process
>>    is close to 50Mb now:
>>
>>     ftp://external.atlantis.dp.ua/FreeBSD/CURRENT/top.txt
>>
>>    Is it miscalculation or real growth of virtual address space?
>> 
>> 
> I believe this is the new malloc code in libc, I am seeing this on my
> Athlon64 machine, now it likes swap memory, in the old days, it seldom
> touched it.

   I've just compiled a sample program under week-old CURRENT:

#include <stdio.h>
main()
{
     putchar('\n');
     for(;;);
}

Without putchar() call my program's virtual address space isn't so big:

   PID USERNAME  THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
52126 root        1 127    0  1244K   440K RUN      0:31 43.97% a.out

But with putchar() it gives us

   PID USERNAME  THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
58959 root        1 130    0 50100K   632K RUN      0:03 47.19% a.out

What't the reason of so terrible virtual memory consumption? I don't believe
that just plain stdio buffering requires 50 Mbytes (!) of virtual address
space.

Sincerely, Dmitry
-- 
Atlantis ISP, System Administrator
e-mail:  dmitry_at_atlantis.dp.ua
nic-hdl: LYNX-RIPE
Received on Thu Feb 16 2006 - 11:16:03 UTC

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