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Date:      Mon, 15 Jul 2002 18:37:59 -0400
From:      Bosko Milekic <bmilekic@unixdaemons.com>
To:        "?$BED0fD>G7?(B" <naoyuki_tai@mac.com>
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   Re: mbuf clusters behavior (NMBCLUSTERS)
Message-ID:  <20020715183759.A38238@unixdaemons.com>
In-Reply-To: <86k7nwwttv.wl@mac.com>; from naoyuki_tai@mac.com on Mon, Jul 15, 2002 at 05:43:24PM -0400
References:  <86k7nwwttv.wl@mac.com>

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On Mon, Jul 15, 2002 at 05:43:24PM -0400, ?$BED0fD>G7?(B wrote:
[...]
> If I do not suspend the copy command, the mbuf clusters hit the
> max and the server starts to drop the packets. It slows down the nfs 
> serving severly due to its nfs retry.

 Are you sure that you're actually running out of address space? (i.e.,
 does `netstat -m' finally show a totally exhausted cluster pool?)
 It is also possible to get the messages you mention if, for example,
 you run out of available RAM.

> How can I prevent this "mbuf clusters exhaustion"?

 Assuming this is really you running out of clusters or mbufs because
 NMBCLUSTERS is too low and not because you're out of RAM, you can take
 a look at setting per-UID sbsize (socket buffer) limits.

> Increasing mbuf clusters is not an option. There is no way that I 
> can allocate big enough for all of files I copy.
> 
> Relating to this, I do not understand why that the mbuf clusters
> are not freed fast enough. I watched "top" and it does seem to be
> that CPU is not exhausted.
> After all, I'm copying less than 10Mbyte/sec, probably 6 - 7 Mbytes
> at most.
> Hard disk is a Seagate ATA/IV 60Gbyte.The drive is hooked up to a 
> Promise PCI ATA/UDMA 100 controller card.
> bonnie shows that it can sustain 15M - 20M bytes read/write. 

 Uhm, I've been following you up to this point.  I'm not sure why
 clusters are not being released faster, either, however: what exactly
 are you copying from, and what are you copying to?  I'm assuming you're
 copying to an NFS mount somewhere?

> Is there anything I can try?

 Check your memory usage in top.

> Thank you!
> 
> -- 
> ntai@mac.com, Naoyuki "Tai" Tai
> 
> P.S.
> 
> I sent this message to freebsd-questions, but, did not get any
> response. If you've seen this message before, sorry.

Regards,
-- 
Bosko Milekic
bmilekic@unixdaemons.com
bmilekic@FreeBSD.org


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