From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3AE08D0F.C73ED990@routefree.com> Date: Fri, 20 Apr 2001 12:25:03 -0700 From: David Blythe MIME-Version: 1.0 To: "Billalabeitia, Jose Carlos (IndSys, GEPM)" Cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: Initrd and system used memory References: Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: "Billalabeitia, Jose Carlos (IndSys, GEPM)" wrote: > > Hi everybody: > > Despite the fact that this title may sound like the problem is > already solved, > I have some questions about it. First of all, I have to tell you that am > working with > a 006C board and with our own prototype board, and both of them have > 16MB of RAM. I have already got Linux 2.4.0 (test13-pre3) running on both of > them, > with an initrd and sash as the stand alone shell. Further in this email > there are more > details about the configuration and set up. > > The problem has to do with the size of the initrd. Here are some numbers > that > detail the issue: > > initrd total used free shared > buffers cached > ------- ------ ------- ----- > --------- --------- ---------- > 4MB 15.699.968 6.660.096 9.039.872 2.236.416 4.194.304 > 1.257.472 > 6MB 15.699.968 9.056.256 6.643.712 2.400.256 6.291.456 > 1.323.008 > 8MB 15.699.968 11.366.400 4.333.568 2.408.448 8.388.608 > 1.323.008 > > Initially the filesystem occupies about 1.1MB and as you can see here, the > greater > the initrd is the larger the amount used memory is and the lower the free > memory > available for the filesystem and system. I thought that part of the used > memory was > really allocated for the filesystem but every time I add a new file to the > file system, > the free memory gets reduced and the used memory increased. > > My questions are: > > 1.- Why have I got so much used memory at the start-up time? What > is this memory used for? The ram disk will cause a fixed set of buffers to be grabbed equal to the size of the ram disk. This memory will be included in the tally under the buffers heading. I recently did some analysis of where all the memory was going on our 16M system (not the same board, but still an embedded ppc system) and found that the static kernel uses about 2M, allocates another 20-30 pages during initialization, and most of the remaining kernel allocations show up in /proc/slabinfo (for our running system approx 350 pages). Everything else is user mode stuff (apps + shared libraries such as libc.so, ld.so if you are using shared libraries, etc.). > > 2.- what is wrong in all this ? (see the configuration bellow) > The numbers look reasonable to me. david ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/