Re: [libvirt] [PATCH v3] libvirtd: Increase NL buffer size for lots of interface
On 01/11/2016 05:44 AM, Martin Kletzander wrote:
On Mon, Jan 11, 2016 at 02:59:00PM +0800, Leno Hou wrote:
> 1. When switching CPUs to offline/online in a system more than 128 cpus
> 2. When using virsh to destroy domain in a system with more interface
>
> All of above happens nl_recv returned with error: No buffer space
> available.
> This patch sets the socket buffer size to 128K and turns on message
> peeking
> for nl_recv,as this would solve this problem totally and permanetly.
>
So if none of the above is true/happening...
> Signed-off-by: Leno Hou <houqy(a)linux.vnet.ibm.com>
> Cc: Wenyi Gao <wenyi(a)linux.vnet.ibm.com>
> CC: Laine Stump <laine(a)laine.org>
> CC: Michal Privoznik <mprivozn(a)redhat.com>
> ---
> src/util/virnetlink.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
> index 679b48e..ea65cbc 100644
> --- a/src/util/virnetlink.c
> +++ b/src/util/virnetlink.c
> @@ -65,10 +65,12 @@ struct virNetlinkEventHandle {
>
> # ifdef HAVE_LIBNL1
> # define virNetlinkAlloc nl_handle_alloc
> +# define virSocketSetBufferSize nl_set_buffer_size
> # define virNetlinkFree nl_handle_destroy
> typedef struct nl_handle virNetlinkHandle;
> # else
> # define virNetlinkAlloc nl_socket_alloc
> +# define virSocketSetBufferSize nl_socket_set_buffer_size
> # define virNetlinkFree nl_socket_free
> typedef struct nl_sock virNetlinkHandle;
> # endif
> @@ -696,6 +698,14 @@ virNetlinkEventServiceStart(unsigned int
> protocol, unsigned int groups)
> goto error_server;
> }
>
> + if (virSocketSetBufferSize(srv->netlinknh, 131702, 0) < 0) {
> + virReportSystemError(errno,
> + "%s",_("cannot set netlink socket buffer size to
> 128k"));
> + goto error_server;
> + }
> +
> + nl_socket_enable_msg_peek(srv->netlinknh);
> +
... shouldn't this be non-fatal just in case?
I at first agreed with this [*] if we just issue a warning and continue
we would have the least possibility of regression on older systems (or
maybe some odd/old system that didn't allow setting a 128k buffer?). But
on the other hand, I think the likelyhood of this is very low, and if it
*does* happen we (the developers/maintainers) want to know about it. If
there's a warning in a log file and libvirt continues to operate, the
user isn't likely to report it. If there is an error message and
something doesn't work, then we will definitely hear about it. So I
think this should remain as an error.
Any other opinions?
BTW, otherwise ACK on the change - I backported it to libvirt-0.10.2 and
it built on RHEL6 (which uses libnl1) without problem.
[*](every other error condition in virNetlinkEvenServiceStart() is due
to a condition that would make the netlink listener completely
non-functional, so it makes sense to shut it down. But if we failed to
set the socket buffer size as requested, it would still function on
*most* systems.
> if ((srv->eventwatch = virEventAddHandle(fd,
> VIR_EVENT_HANDLE_READABLE,
> virNetlinkEventCallback,
> --
> 1.9.1
>
> --
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