Re: vmstat's entries type

Michal Mertl <mime_at_traveller.cz> wrote:
 > Recent thread "2Gb SYSVSHM limitation" reminded me of my recent finding
 > - fields in struct vmmeter (src/sys/sys/vmmeter.h) are int and not long.

I'm not authoritative, but I think they should be neither
int nor long, but uint64_t.

 > On an AMD64 machine which can easily make milion syscalls/second the
 > counters seem unnecessarily restricted by being 32bit (u_int).

You don't need an AMD64 machine for that.  I've seen the
counters in the "vmstat -s" output overflow even on slow
(by today's measures) intel machines after a certain amount
of uptime.

 > P.S.: If a commiter expresses some interest in the subject I can work
 > out a patch as I just love stats with huge numbers :-).

Should be fairly easy, I think.  The stats are recorded in
sysctl variables (e.g. vm.stats.sys.v_swtch), so you have
to change the data type of the sysctl, then grep the code
for all occurences that access it (kernel as well as user-
land).

However, there's one small problem:  On 32bit architectures
like i386, a 64bit value can't be changed with a single
instruction.  That might be an efficiency problem, and you
also might have to make sure that proper locking is used
each time the value is accessed.

Best regards
   Oliver

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Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
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