Date: Fri, 23 Mar 2012 12:51:05 +0000 From: Traiano Welcome <Traiano.Welcome@mtnbusiness.co.za> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: FreeBSD: syslog-ng: I/O error occurred while writing; fd='xx', error='No buffer space available (yy)' Message-ID: <CB923D35.E073%traiano.welcome@mtnbusiness.co.za> In-Reply-To: <201203221349.26701.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi John
On 22/03/2012 19:49, "John Baldwin" <jhb@freebsd.org> wrote:
>On Thursday, March 22, 2012 11:00:35 am Traiano Welcome wrote:
>> Hi John
>>=20
>>=20
>>=20
>> On 22/03/2012 14:16, "John Baldwin" <jhb@freebsd.org> wrote:
>>=20
>> >On Thursday, March 22, 2012 6:03:21 am Traiano Welcome wrote:
>> >> Hi List
>> >>=20
>> >> I've been seeing the following in the messages log of my freebsd
>>syslog
>> >> server for quite some time now:
>> >>=20
>> >> ---
>> >> Mar 20 12:19:12 syslog2 syslog-ng[35313]: I/O error occurred while
>> >> writing; fd=3D'12', error=3D'No buffer space available (55)'
>> >> Mar 20 12:19:12 syslog2 syslog-ng[35313]: Connection broken;
>> >> time_reopen=3D'60'
>> >> Mar 20 12:19:12 syslog2 syslog-ng[35313]: I/O error occurred while
>> >> writing; fd=3D'13', error=3D'No buffer space available (55)'
>> >> Mar 20 12:19:12 syslog2 syslog-ng[35313]: Connection broken;
>> >> time_reopen=3D'60'
>> >> ---
>> >>=20
>> >> These happen at a frequency of about 7 per minute on average. See
>> >>attached
>> >> trend graphs for an idea of the volume of traffic we're doing, as
>>well
>> >>as
>> >> the memory and cpu utilisation trends on this server during this
>>period.
>> >> As can be seen from the graphs, load does not seem to be the issue.
>> >> Occasionally during the week, the system freezes and requires a
>>reboot,
>> >>I
>> >> think it's related to the above message, though I'm not sure.
>> >>=20
>> >> My question is: What does this error mean, and how can I resolve it?
>> >>=20
>> >> I have tried to frame this as an operating system kernel resource
>>issue,
>> >> and experimented with increasing the freebsd kernel sysctls for UDP
>> >> performance:
>> >
>> >It means that the network driver has "filled" up with packets. Are you
>> >using=20
>> >igb(4)? We have to crank the number of descriptors assigned to igb to
>> >the max=20
>> >to workaround this at work (we get DNS timeouts during a simple boot
>> >otherwise). hw.igb.maxtxd is the tunable you would set. The max value
>> >you=20
>> >can set it to is 4096.
>>=20
>>=20
>> Thanks for the clue. It seems igb is indeed being used. However, I not
>> that when I try to list this tunable, I don't get anything:
>>=20
>> ---
>> [root@syslog2]# sysctl -a | grep igb
>> [root@syslog2]#
>> ---
>>=20
>>=20
>> ---
>> [root@syslog2 /boot]# sysctl hw.igb.maxtxd=3D4000
>> sysctl: unknown oid 'hw.igb.maxtxd'
>
>> ---
>>=20
>>=20
>> Is this due to the way igb is compiled into the kernel, or am I tuning
>>in
>> the wrong place :-)
>
>You need to put it in /boot/loader.conf and then reboot. Do try using
>4096
>rather than 4000.
I'm an idiot :-) Looks like the correct driver is bce:
---
[root@syslog2]# sysctl dev.bce | grep -v stat
dev.bce.0.%desc: Broadcom NetXtreme II BCM5708 1000Base-T (B2)
dev.bce.0.%driver: bce
dev.bce.0.%location: slot=3D0 function=3D0
dev.bce.0.%pnpinfo: vendor=3D0x14e4 device=3D0x164c subvendor=3D0x1028
subdevice=3D0x01b3 class=3D0x020000
dev.bce.0.%parent: pci7
dev.bce.0.l2fhdr_error_count: 0
dev.bce.0.mbuf_alloc_failed_count: 0
dev.bce.0.fragmented_mbuf_count: 0
dev.bce.0.dma_map_addr_rx_failed_count: 0
dev.bce.0.dma_map_addr_tx_failed_count: 0
dev.bce.0.unexpected_attention_count: 0
dev.bce.0.com_no_buffers: 0
dev.bce.1.%desc: Broadcom NetXtreme II BCM5708 1000Base-T (B2)
dev.bce.1.%driver: bce
dev.bce.1.%location: slot=3D0 function=3D0
dev.bce.1.%pnpinfo: vendor=3D0x14e4 device=3D0x164c subvendor=3D0x1028
subdevice=3D0x01b3 class=3D0x020000
dev.bce.1.%parent: pci3
dev.bce.1.l2fhdr_error_count: 0
dev.bce.1.mbuf_alloc_failed_count: 0
dev.bce.1.fragmented_mbuf_count: 0
dev.bce.1.dma_map_addr_rx_failed_count: 0
dev.bce.1.dma_map_addr_tx_failed_count: 0
dev.bce.1.unexpected_attention_count: 0
dev.bce.1.com_no_buffers:
---
And it looks like the buffer full errors have returned, and the perceived
improvement may just have been due to traffic backoff due to the reboot
But I can't seem to find any tunables for the bce driver. The man page
only indicates one:
---
SYSCTL VARIABLES
The following variables are available as both sysctl(8) variables and
loader(8) tunables:
hw.bce.msi_enable
Whether or not MSI support is enabled in the driver. The
default
value is 1.
---
The only other solution I can think of is an upgrade. Is there an
alternative to this ?
>
>--=20
>John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CB923D35.E073%traiano.welcome>