On Wed, Dec 3, 2014 at 5:52 PM, Michael S. Tsirkin <[email protected]>
wrote:
On Wed, Dec 03, 2014 at 12:49:37PM +0530, Pankaj Gupta wrote:
Networking under kvm works best if we allocate a per-vCPU RX and TX
queue in a virtual NIC. This requires a per-vCPU queue on the host
side.
It is now safe to increase the maximum number of queues.
Preceding patche: 'net: allow large number of rx queues'
s/patche/patch/
made sure this won't cause failures due to high order memory
allocations. Increase it to 256: this is the max number of vCPUs
KVM supports.
Signed-off-by: Pankaj Gupta <[email protected]>
Reviewed-by: David Gibson <[email protected]>
Hmm it's kind of nasty that each tun device is now using x16 memory.
Maybe we should look at using a flex array instead, and removing the
limitation altogether (e.g. make it INT_MAX)?
But this only happens when IFF_MULTIQUEUE were used.
And core has vmalloc() fallback.
So probably not a big issue?
---
drivers/net/tun.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e3fa65a..a19dc5f8 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -113,10 +113,11 @@ struct tap_filter {
unsigned char addr[FLT_EXACT_COUNT][ETH_ALEN];
};
-/* DEFAULT_MAX_NUM_RSS_QUEUES were chosen to let the rx/tx queues
allocated for
- * the netdevice to be fit in one page. So we can make sure the
success of
- * memory allocation. TODO: increase the limit. */
-#define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
+/* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
+ * to max number of vCPUS in guest. Also, we are making sure here
+ * queue memory allocation do not fail.
It's not queue memory allocation anymore, is it?
I would say "
This also helps the tfiles field fit in 4K, so the whole tun
device only needs an order-1 allocation.
"
+ */
+#define MAX_TAP_QUEUES 256
#define MAX_TAP_FLOWS 4096
#define TUN_FLOW_EXPIRE (3 * HZ)
--
1.8.3.1
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