Re: 2.1.91pre2 death by swapping.

Dr. Werner Fink (werner@suse.de)
Thu, 26 Mar 1998 14:00:53 +0100

>
> Hi,
> Well, shortly after I wrote my previous message, 2.1.91pre2 died a nasty
> death. This system has 64mb RAM and was lightly loaded, the main thing
> it was doing was playing a MOD. It started to swap out of the blue, the
> mod started skipping more and more, and eventually stopped playing
> entiredly while the machine thrashed. It continued thrashing for 10-15
> minutes, every program totally stopped while this was happening. Using
> the magic sysrq show memory option, I could see that the free pages
> number was fluctuating between 10200 and 10250 or so. Eventually I rebooted
> back to 2.1.90 with the magic sysrq.
> -Myrdraal

I've found the following piece of code in the 2.1.91pre2:

--------------------------------------------------------------------------
--- v2.1.90/linux/mm/filemap.c Tue Mar 10 10:03:36 1998
+++ linux/mm/filemap.c Wed Mar 25 13:13:36 1998
@@ -150,6 +150,10 @@
}
tmp = tmp->b_this_page;
} while (tmp != bh);
+
+ /* Refuse to swap out all buffer pages */
+ if ((buffermem >> PAGE_SHIFT) * 100 > (buffer_mem.min_percent * num_physpages))
+ goto next;
}

/* We can't throw away shared pages, but we do mark
--------------------------------------------------------------------------

IMHO the `>' should be a `<', shouldn't it?

... and the better place fur such a statement is IMHO
linux/mm/vmscan.c:do_try_to_free_page() which would avoid the shrink_mmap()
and its do-while-loop.

Werner

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