Messages in this thread | | | From | Keith Owens <> | Subject | Re: IPC/Shared memory automatic freeing ? | Date | Tue, 16 Mar 1999 17:09:13 -0800 |
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On Wed, 17 Mar 1999 01:29:54 +0100 (CET), Eric Estievenart <eric@via.ecp.fr> wrote: >Working and debugging a small proggy using IPC shared memory >with some friends, we had some memory segments not freed >when it didn't finish normally. > >Of course, I do not propose to free the pages as soon as the >number of attachements reaches zero (damned developpers that >detach and exit before a child has attached hisself to the >segment... ;), but we could reuse the resources if they are >not attached and unused for some amount of time (using >the shm_ctime info).
It is legal for an application to create a shared memory page once then let other programs store data as required, with a periodic program to copy the results to disk. If the flush program and the other programs are not running *right now* then the use count is zero. It does not mean that the kernel can reap the storage.
This is absolutely an application policy problem, the kernel must keep its nose out. If an administrator really cares about this, they can implement their own policy with a cron job that uses ipcs and ipcrm as required for that site.
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