Thread (1 message) 1 message, 1 author, 2015-08-04

Re: [PATCH net-next v2] openvswitch: Make 100 percents packets sampled when sampling rate is 1.

From: Pravin Shelar <hidden>
Date: 2015-08-04 22:00:28

On Mon, Aug 3, 2015 at 9:07 PM, Wenyu Zhang [off-list ref] wrote:
When sampling rate is 1, the sampling probability is UINT32_MAX. The packet
should be sampled even the prandom_u32() generate the number of UINT32_MAX.
And none packet need be sampled when the probability is 0.

Signed-off-by: Wenyu Zhang <redacted>
Patch looks good, I have following minor comments.
quoted hunk
---
 net/openvswitch/actions.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index cf04c2f..c81bcf5 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -669,9 +669,11 @@ static int sample(struct datapath *dp, struct sk_buff *skb,

        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
+               uint32_t probability;
                switch (nla_type(a)) {
There should be blank line after variable definitions.
                case OVS_SAMPLE_ATTR_PROBABILITY:
-                       if (prandom_u32() >= nla_get_u32(a))
+                       probability = nla_get_u32(a);
+                       if (!probability || prandom_u32() > probability)
                                return 0;
                        break;
I got following warning on checkpatch.pl

./scripts/checkpatch.pl
0001-openvswitch-Make-100-percents-packets-sampled-when-s.patch

CHECK: Prefer kernel type 'u32' over 'uint32_t'

#24: FILE: net/openvswitch/actions.c:672:

+ uint32_t probability;


total: 0 errors, 0 warnings, 1 checks, 12 lines checked
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