Messages in this thread | | | Date | Wed, 18 Sep 2002 12:54:06 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] recognize MAP_LOCKED in mmap() call |
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Mark_H_Johnson@raytheon.com wrote: > > Andrew Morton wrote: > >(SuS really only anticipates that mmap needs to look at prior mlocks > >in force against the address range. It also says > > > > Process memory locking does apply to shared memory regions, > > > >and we don't do that either. I think we should; can't see why SuS > >requires this.) > > Let me make sure I read what you said correctly. Does this mean that Linux > 2.4 (or 2.5) kernels do not lock shared memory regions if a process uses > mlockall?
Linux does lock these regions. SuS seems to imply that we shouldn't. But we should.
> If not, that is *really bad* for our real time applications. We don't want > to take a page fault while running some 80hz task, just because some > non-real time application tried to use what little physical memory we allow > for the kernel and all other applications. > > I asked a related question about a week ago on linux-mm and didn't get a > response. Basically, I was concerned that top did not show RSS == Size when > mlockall(MCL_CURRENT|MCL_FUTURE) was called. Could this explain the > difference or is there something else that I'm missing here? >
That mlockall should have faulted everything in. It could be an accounting bug, or it could be a bug. That's not an aspect which gets tested a lot. I'll take a look. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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