[libvirt] [PATCH v3] libvirtd: Increase NL buffer size for lots of interface

[Martin Kletzander]

On Mon, Jan 11, 2016 at 02:32:44PM -0500, Laine Stump wrote:
>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 at linux.vnet.ibm.com>
>>>Cc: Wenyi Gao <wenyi at linux.vnet.ibm.com>
>>>CC: Laine Stump <laine at laine.org>
>>>CC: Michal Privoznik <mprivozn at 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.
>

Well, we might want to know about it, I just don't see the benefit of
it.  Anyway, it's ok with me the way it is now as well.  I was just
wondering.

Have a nice day,
Martin
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