From 29b4433d991c88d86ca48a4c1cc33c671475be4b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 11 Oct 2010 10:22:12 +0000 Subject: net: percpu net_device refcount We tried very hard to remove all possible dev_hold()/dev_put() pairs in network stack, using RCU conversions. There is still an unavoidable device refcount change for every dst we create/destroy, and this can slow down some workloads (routers or some app servers, mmap af_packet) We can switch to a percpu refcount implementation, now dynamic per_cpu infrastructure is mature. On a 64 cpus machine, this consumes 256 bytes per device. On x86, dev_hold(dev) code : before lock incl 0x280(%ebx) after: movl 0x260(%ebx),%eax incl fs:(%eax) Stress bench : (Sending 160.000.000 UDP frames, IP route cache disabled, dual E5540 @2.53GHz, 32bit kernel, FIB_TRIE) Before: real 1m1.662s user 0m14.373s sys 12m55.960s After: real 0m51.179s user 0m15.329s sys 10m15.942s Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/infiniband/hw/nes/nes_verbs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/infiniband/hw/nes/nes_verbs.c') diff --git a/drivers/infiniband/hw/nes/nes_verbs.c b/drivers/infiniband/hw/nes/nes_verbs.c index 9046e6675686..546fc22405fe 100644 --- a/drivers/infiniband/hw/nes/nes_verbs.c +++ b/drivers/infiniband/hw/nes/nes_verbs.c @@ -785,7 +785,7 @@ static struct ib_pd *nes_alloc_pd(struct ib_device *ibdev, nes_debug(NES_DBG_PD, "nesvnic=%p, netdev=%p %s, ibdev=%p, context=%p, netdev refcnt=%u\n", nesvnic, nesdev->netdev[0], nesdev->netdev[0]->name, ibdev, context, - atomic_read(&nesvnic->netdev->refcnt)); + netdev_refcnt_read(nesvnic->netdev)); err = nes_alloc_resource(nesadapter, nesadapter->allocated_pds, nesadapter->max_pd, &pd_num, &nesadapter->next_pd); @@ -1416,7 +1416,7 @@ static struct ib_qp *nes_create_qp(struct ib_pd *ibpd, /* update the QP table */ nesdev->nesadapter->qp_table[nesqp->hwqp.qp_id-NES_FIRST_QPN] = nesqp; nes_debug(NES_DBG_QP, "netdev refcnt=%u\n", - atomic_read(&nesvnic->netdev->refcnt)); + netdev_refcnt_read(nesvnic->netdev)); return &nesqp->ibqp; } -- cgit v1.2.3