| Message ID | ada3ahbccdk.fsf@cisco.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Roland Dreier <rdreier@cisco.com> Date: Fri, 28 Nov 2008 21:47:03 -0800 > The function is_pure_response() does "ntohl(var) & const" and then > essentially just tests whether the result is 0 or not; this can be done > more efficiently by computing "var & htonl(const)" instead and doing the > byte swap at compile time instead of run time. > > This change slightly shrinks the compiled code; eg on x86-64 we save a > couple of bswapl instructions: > > add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8) > function old new delta > t3_sge_intr_msix_napi 544 536 -8 > > and this also has the pleasant side effect of fixing a sparse warning: > > drivers/net/cxgb3/sge.c:2313:15: warning: restricted degrades to integer > > Signed-off-by: Roland Dreier <rolandd@cisco.com> Applied, thanks Roland. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c index c6480be..4181373 100644 --- a/drivers/net/cxgb3/sge.c +++ b/drivers/net/cxgb3/sge.c @@ -2308,7 +2308,7 @@ next_fl: static inline int is_pure_response(const struct rsp_desc *r) { - u32 n = ntohl(r->flags) & (F_RSPD_ASYNC_NOTIF | F_RSPD_IMM_DATA_VALID); + __be32 n = r->flags & htonl(F_RSPD_ASYNC_NOTIF | F_RSPD_IMM_DATA_VALID); return (n | r->len_cq) == 0; }
The function is_pure_response() does "ntohl(var) & const" and then essentially just tests whether the result is 0 or not; this can be done more efficiently by computing "var & htonl(const)" instead and doing the byte swap at compile time instead of run time. This change slightly shrinks the compiled code; eg on x86-64 we save a couple of bswapl instructions: add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8) function old new delta t3_sge_intr_msix_napi 544 536 -8 and this also has the pleasant side effect of fixing a sparse warning: drivers/net/cxgb3/sge.c:2313:15: warning: restricted degrades to integer Signed-off-by: Roland Dreier <rolandd@cisco.com> --- drivers/net/cxgb3/sge.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html