From: Rasmus Villemoes Date: Fri, 16 Jan 2015 14:39:55 +0000 (+0100) Subject: RDMA/ocrdma: Help gcc generate better code for ocrdma_srq_toggle_bit X-Git-Tag: rdma-for-linus^6~2 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=ba64fdca63af5a1bdda8e33d9cc8496089631dde;p=~emulex%2Finfiniband.git RDMA/ocrdma: Help gcc generate better code for ocrdma_srq_toggle_bit gcc emits a surprising amount of code in order to flip a bit. One would think that a single instruction is enough. $ scripts/bloat-o-meter /tmp/ocrdma_verbs.o drivers/infiniband/hw/ocrdma/ocrdma_verbs.o add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-142 (-142) function old new delta ocrdma_post_srq_recv 498 460 -38 ocrdma_poll_cq 2010 1962 -48 ocrdma_discard_cqes 495 439 -56 All three calls of ocrdma_srq_toggle_bit happen within spinlocks, so saving a few useless instructions might be worthwhile. Signed-off-by: Rasmus Villemoes Acked-by: Selvin Xavier Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c index 5f656b936de..c1e9f9617ab 100644 --- a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c +++ b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c @@ -1591,10 +1591,7 @@ static void ocrdma_srq_toggle_bit(struct ocrdma_srq *srq, int idx) int i = idx / 32; unsigned int mask = (1 << (idx % 32)); - if (srq->idx_bit_fields[i] & mask) - srq->idx_bit_fields[i] &= ~mask; - else - srq->idx_bit_fields[i] |= mask; + srq->idx_bit_fields[i] ^= mask; } static int ocrdma_hwq_free_cnt(struct ocrdma_qp_hwq_info *q)