Date: Tue, 16 Jul 2002 10:11:08 -0400 From: Naoyuki Tai <naoyuki_tai@mac.com> To: freebsd-stable@freebsd.org Subject: Re: mbuf clusters behavior (NMBCLUSTERS) Message-ID: <867kjvoj9f.wl@mac.com> In-Reply-To: <20020715183759.A38238@unixdaemons.com> References: <86k7nwwttv.wl@mac.com>
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If someone can answer this question, I can probably start troubleshoot the problem. After nfs server uses up the mbuf clusters, how are the mbuf clusters flushed? Should I try to change "maxusers 0" to a number like 10? One thing I forgot to mention is that the file system uses soft update. Would it matter? At Mon, 15 Jul 2002 18:37:59 -0400, Bosko Milekic wrote: > > 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? Please read the original message again. I believe that I included all the information I can think of. In summary: 1. Simple nfs file copy exhausts the mbuf clusters 2. When mbuf clusters are exhausted, the whole copy process suspends for 10 - 20 seconds. 3. One NFS server: FreeBSD 4.6-stable and Client: RH 7.3 4. I tried various size of mbuf clusters. 5. NMBCLUSTERS is not too low. I assigned more than recommended. 32768 (64M) is for multiuser large scale server. For this case, one server and one client, I gave it the double of it, and it is still no go. 6. The size of mbuf clusters is 128Mbytes and I can not increase any more. > > Is there anything I can try? > > Check your memory usage in top. Why? What do you think that what's hapenning? Slashing? Very unlikely. The FreeBSD server has no other client for the test or any other major service running. If so, I'd have mentioned in the original message. > > 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 > Have a good day! -- ntai@mac.com, Naoyuki "Tai" Tai To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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