Date: Thu, 26 Oct 2006 11:20:05 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Scott Long <scottl@samsco.org> Cc: FreeBSD Stable <freebsd-stable@freebsd.org>, Andreas Sons <sons@zs64.net>, Stefan Bethke <stb@lassitu.de> Subject: Re: panic: kmem_map too small Message-ID: <20061026111723.K33725@fledge.watson.org> In-Reply-To: <20061026091253.J69980@fledge.watson.org> References: <CD619308-6B7B-4B68-B011-CE979D67E0C1@lassitu.de> <20061025183308.L33725@fledge.watson.org> <838FCA83-20F8-4A09-A025-E69956032F86@lassitu.de> <45400286.9020402@samsco.org> <20061026091253.J69980@fledge.watson.org>
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On Thu, 26 Oct 2006, Robert Watson wrote:
> On Wed, 25 Oct 2006, Scott Long wrote:
>
>> There are no obvious culprits from what you posted. The kernel was only
>> trying to allocate 60 bytes, and the 64-byte bucket didn't look to be
>> overly used. None of the other zones look terribly over-used either. The
>> 'show malloc' command doesn't really give enough stats to be terribly
>> useful, IMHO.
>
> What would you add to the output to make it more useful? The main
> difference between "show malloc" and "vmstat -m", other than any "use over
> time" associated with multiple runs of vmstat -m, is the malloc size
> bitmask. This is relatively easily added to kern_malloc.c.
>
>> And neither of the commands can effectively track things like contig memory
>> allocator. Can you try the following two commands:
>
> Want to add "show contigmalloc"?
>
> I've found it significantly easier to debug memory leaks since adding these
> DDB commands, but they are easily enhanced to carry more information than
> they do now.
After a bit of looking at the output, etc, I agree with your conclusion that
what's there now is lacking. The attached patch, committed to -CURRENT but
not yet to -STABLE, makes the "show malloc" DDB output a bit more like the
"vmstat -m" output, in that it summarizes the allocation counts and adds the
memory use information. Sample output:
db> show malloc
Type InUse MemUse Requests
GEOM 111 14K 529
fw_xfer 0 0K 0
$PIR 0 0K 0
pfs_vncache 0 0K 0
pfs_nodes 20 3K 20
nexusdev 2 1K 2
This is much more useful for malloc types that see variable size allocation,
rather than fixed-size allocation, and aligns better with what is offered by
user space vmstat -m. I still don't implement interpretting the size mask, as
occurs in user space.
Robert N M Watson
Computer Laboratory
University of Cambridge
Index: kern_malloc.c
===================================================================
RCS file: /zoo/cvsup/FreeBSD-CVS/src/sys/kern/kern_malloc.c,v
retrieving revision 1.155
diff -u -r1.155 kern_malloc.c
--- kern_malloc.c 23 Jul 2006 19:55:41 -0000 1.155
+++ kern_malloc.c 26 Oct 2006 10:13:42 -0000
@@ -802,20 +802,26 @@
struct malloc_type_internal *mtip;
struct malloc_type *mtp;
u_int64_t allocs, frees;
+ u_int64_t alloced, freed;
int i;
- db_printf("%18s %12s %12s %12s\n", "Type", "Allocs", "Frees",
- "Used");
+ db_printf("%18s %12s %12s %12s\n", "Type", "InUse", "MemUse",
+ "Requests");
for (mtp = kmemstatistics; mtp != NULL; mtp = mtp->ks_next) {
mtip = (struct malloc_type_internal *)mtp->ks_handle;
allocs = 0;
frees = 0;
+ alloced = 0;
+ freed = 0;
for (i = 0; i < MAXCPU; i++) {
allocs += mtip->mti_stats[i].mts_numallocs;
frees += mtip->mti_stats[i].mts_numfrees;
+ alloced += mtip->mti_stats[i].mts_memalloced;
+ freed += mtip->mti_stats[i].mts_memfreed;
}
- db_printf("%18s %12ju %12ju %12ju\n", mtp->ks_shortdesc,
- allocs, frees, allocs - frees);
+ db_printf("%18s %12ju %12juK %12ju\n",
+ mtp->ks_shortdesc, allocs - frees,
+ (alloced - freed + 1023) / 1024, allocs);
}
}
#endif
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