* [PATCH net-next] tcp: remove conditional branches from tcp_mstamp_refresh()
@ 2019-03-22 13:26 Eric Dumazet
2019-03-24 1:44 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2019-03-22 13:26 UTC (permalink / raw)
To: David S . Miller; +Cc: netdev, Eric Dumazet, Eric Dumazet
tcp_clock_ns() (aka ktime_get_ns()) is using monotonic clock,
so the checks we had in tcp_mstamp_refresh() are no longer
relevant.
This patch removes cpu stall (when the cache line is not hot)
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/ipv4/tcp_output.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4522579aaca2d24b7be61abac658a3c8cbd2b960..e265d1aeeb66996da3903eef383eaec9a320cce0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -52,12 +52,8 @@ void tcp_mstamp_refresh(struct tcp_sock *tp)
{
u64 val = tcp_clock_ns();
- if (val > tp->tcp_clock_cache)
- tp->tcp_clock_cache = val;
-
- val = div_u64(val, NSEC_PER_USEC);
- if (val > tp->tcp_mstamp)
- tp->tcp_mstamp = val;
+ tp->tcp_clock_cache = val;
+ tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC);
}
static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
--
2.21.0.392.gf8f6787159e-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next] tcp: remove conditional branches from tcp_mstamp_refresh()
2019-03-22 13:26 [PATCH net-next] tcp: remove conditional branches from tcp_mstamp_refresh() Eric Dumazet
@ 2019-03-24 1:44 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2019-03-24 1:44 UTC (permalink / raw)
To: edumazet; +Cc: netdev, eric.dumazet
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 22 Mar 2019 06:26:29 -0700
> tcp_clock_ns() (aka ktime_get_ns()) is using monotonic clock,
> so the checks we had in tcp_mstamp_refresh() are no longer
> relevant.
>
> This patch removes cpu stall (when the cache line is not hot)
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-03-22 13:26 [PATCH net-next] tcp: remove conditional branches from tcp_mstamp_refresh() Eric Dumazet
2019-03-24 1:44 ` David Miller
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