Re: RH30: Virtual Mem shot heavily by locale-archive...

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Fri, 30 Sep 2005, Arijit Das wrote:

> I have RH3.0 installed in an AMD64 machine.
>  
> In this system, when I look at the virtual address space mappings of a process (say a sleep process), I find that almost 80% of its virtual address space has been taken by a private copy of /usr/lib/locale/locale-archive mapped to its virtual address space by default. Check this:
>  
>      31396 KB    r--p    /usr/lib/locale/locale-archive
>  
> Total Virtual Memory = 38816 KB
> On the other hand, when I look at the same info in a RH7.2 system, I see that a few small set of essential locale files have been mapped whose overall summed up size is around 236KB (way smaller than RH3.0)...Check this:
>          4    r--p    /usr/lib/locale/en_US/LC_IDENTIFICATION
>          4    r--p    /usr/lib/locale/en_US/LC_MEASUREMENT
>          4    r--p    /usr/lib/locale/en_US/LC_TELEPHONE
>          4    r--p    /usr/lib/locale/en_US/LC_ADDRESS
>          4    r--p    /usr/lib/locale/en_US/LC_NAME
>          4    r--p    /usr/lib/locale/en_US/LC_PAPER
>          4    r--p    /usr/lib/locale/en_US/LC_MESSAGES/SYS_LC_MESSAGES
>          4    r--p    /usr/lib/locale/en_US/LC_MONETARY
>         24    r--p    /usr/lib/locale/en_US/LC_COLLATE
>          4    r--p    /usr/lib/locale/en_US/LC_TIME
>          4    r--p    /usr/lib/locale/en_US/LC_NUMERIC
>        172    r--p    /usr/lib/locale/en_US/LC_CTYPE
> This seems like a huge requirement of memory for each small process executed in the RH3.0 system and hence, shots up the memory requirement of the entire system because the mapped region /usr/lib/locale/locale-archive is privately mapped.
>  
> Question: 
>  1) Is there any way by which I can instruct my RH3.0 system not to map the huge locale-archive file by default? Rather it should map the few small set of locale files, as mapped in RH7.2 system.
>  2) If the answer of my previous question is yes (it is possible), then what will be the impact of doing that?
>  
> You can find the sample "sleep" commands below.
>  
> Thanks,
> Arijit
>  
> RH3.0 on AMD64:
> =============
> vgamd126:arijit>sleep 400 &                                                                                    
> [1] 19916
> vgamd126:arijit>pmap 19916
>  Size (KB)    Perm    Associated files (if any)                   
> ==========    ====    =============================================
>         16    r-xp    /bin/sleep
>          4    rw-p    /bin/sleep
>        132    rwxp   
>       1108    r-xp    /lib64/ld-2.3.2.so
>          4    rw-p    /lib64/ld-2.3.2.so
>          4    rw-p   
>        540    r-xp    /lib64/tls/libm-2.3.2.so
>       1024    ---p    /lib64/tls/libm-2.3.2.so
>          4    rw-p    /lib64/tls/libm-2.3.2.so
>          4    rw-p   
>         36    r-xp    /lib64/tls/librtkaio-2.3.2.so
>       1024    ---p    /lib64/tls/librtkaio-2.3.2.so
>          4    rw-p    /lib64/tls/librtkaio-2.3.2.so
>         64    rw-p   
>       1260    r-xp    /lib64/tls/libc-2.3.2.so
>       1024    ---p    /lib64/tls/libc-2.3.2.so
>         20    rw-p    /lib64/tls/libc-2.3.2.so
>         16    rw-p   
>         60    r-xp    /lib64/tls/libpthread-0.60.so
>       1024    ---p    /lib64/tls/libpthread-0.60.so
>          4    rw-p    /lib64/tls/libpthread-0.60.so
>         20    rw-p   
>      31396    r--p    /usr/lib/locale/locale-archive
>         24    rw-p   
> Total Virtual Memory = 38816 KB
> vgamd126:arijit>
>  
>  
> RH7.2 in i686
> ==========
> eurika120:arijit>sleep 400 &                                                                                           
> [1] 11065
> eurika120:arijit>pmap 11065
>  Size (KB)    Perm    Associated files (if any)                   
> ==========    ====    =============================================
>         12    r-xp    /bin/sleep
>          4    rw-p    /bin/sleep
>          8    rwxp   
>         88    r-xp    /lib/ld-2.2.4.so
>          4    rw-p    /lib/ld-2.2.4.so
>          4    r--p    /usr/lib/locale/en_US/LC_IDENTIFICATION
>          4    r--p    /usr/lib/locale/en_US/LC_MEASUREMENT
>          4    r--p    /usr/lib/locale/en_US/LC_TELEPHONE
>          4    r--p    /usr/lib/locale/en_US/LC_ADDRESS
>          4    r--p    /usr/lib/locale/en_US/LC_NAME
>          4    r--p    /usr/lib/locale/en_US/LC_PAPER
>          4    r--p    /usr/lib/locale/en_US/LC_MESSAGES/SYS_LC_MESSAGES
>          4    r--p    /usr/lib/locale/en_US/LC_MONETARY
>         24    r--p    /usr/lib/locale/en_US/LC_COLLATE
>          4    r--p    /usr/lib/locale/en_US/LC_TIME
>          4    r--p    /usr/lib/locale/en_US/LC_NUMERIC
>          4    rw-p   
>        136    r-xp    /lib/i686/libm-2.2.4.so
>          4    rw-p    /lib/i686/libm-2.2.4.so
>         28    r-xp    /lib/librt-2.2.4.so
>          4    rw-p    /lib/librt-2.2.4.so
>         40    rw-p   
>       1224    r-xp    /lib/i686/libc-2.2.4.so
>         20    rw-p    /lib/i686/libc-2.2.4.so
>         16    rw-p   
>         52    r-xp    /lib/i686/libpthread-0.9.so
>         32    rw-p    /lib/i686/libpthread-0.9.so
>        172    r--p    /usr/lib/locale/en_US/LC_CTYPE
>         24    rwxp   
> Total Virtual Memory = 1936 KB
> eurika120:arijit>
>

Those private mappings are much smaller than the whole shared
libraries. They are probably gap-fillers because the libraries
don't end on page boundaries and mapping is per-page. The
gap-fillers shown as "---p" will have PROT_NONE attributes
and therefore can't be read/written/exec, etc. In other words,
it's perfectly normal and you wouldn't want to do anything about it.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.

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