Paul Barton-Davis <pbd@Op.Net> writes:
> There are a lot of questions and problems coming up related to the new
> shm filesystem. I haven't noticed a pointer to any docs that we can
> read to help us solve the problems for ourselves. Does anyone know of
> any such thing ?
>
> My own personal problem is understanding this:
>
> pbd[93]>cat /proc/sys/kernel/shmmax
> 33554432
> pbd[94]>df
> Filesystem 1k-blocks Used Available Use% Mounted on
> none 4194304 0 4194304 0% /var/shm
> [ ... etc. ... ]
>
> How do these numbers relate to each other ? How do I increase the
> amount of shm available, and what are the consequences of doing so ?
They do not relate: shmmax is the maximum size of one shm segment. The
size of the fs is the number of all blocks allocated to shm objects.
>From /usr/src/linux/ipc/shm.c:
* There are the following mount options:
* - nr_blocks (^= shmall) is the number of blocks of size PAGE_SIZE
* we are allowed to allocate
* - nr_inodes (^= shmmni) is the number of files we are allowed to
* allocate
* - mode is the mode for the root directory (default S_IRWXUGO | S_ISVTX)
> I've also had my system (SMP 2.3.51 on a dual PII-450) end up with
> dozens of shmid's that don't correspond to any known processes, and
> cannot be removed with ipcrm. Is this a bug ?
There is still one bug in 2.3.99-pre4 known to me, where shmids will
not be removed erroneously. I am working on this.
Greetings
Christoph
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