Eric Dumazet bf368e4e70 net: Avoid extra wakeups of threads blocked in wait_for_packet() ... In 2.6.25 we added UDP mem accounting. This unfortunatly added a penalty when a frame is transmitted, since we have at TX completion time to call sock_wfree() to perform necessary memory accounting. This calls sock_def_write_space() and utimately scheduler if any thread is waiting on the socket. Thread(s) waiting for an incoming frame was scheduled, then had to sleep again as event was meaningless. (All threads waiting on a socket are using same sk_sleep anchor) This adds lot of extra wakeups and increases latencies, as noted by Christoph Lameter, and slows down softirq handler. Reference : http://marc.info/?l=linux-netdev&m=124060437012283&w=2 Fortunatly, Davide Libenzi recently added concept of keyed wakeups into kernel, and particularly for sockets (see commit 37e5540b3c epoll keyed wakeups: make sockets use keyed wakeups) Davide goal was to optimize epoll, but this new wakeup infrastructure can help non epoll users as well, if they care to setup an appropriate handler. This patch introduces new DEFINE_WAIT_FUNC() helper and uses it in wait_for_packet(), so that only relevant event can wakeup a thread blocked in this function. Trace of function calls from bnx2 TX completion bnx2_poll_work() is : __kfree_skb() skb_release_head_state() sock_wfree() sock_def_write_space() __wake_up_sync_key() __wake_up_common() receiver_wake_function() : Stops here since thread is waiting for an INPUT Reported-by: Christoph Lameter <cl@linux.com> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2009-04-28 02:24:21 -07:00
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acpi	Merge branches 'release', 'APERF', 'ARAT', 'misc', 'kelvin', 'device-lock' and 'bjorn.notify' into release	2009-04-07 18:18:42 -04:00
asm-arm
asm-generic	percpu: unbreak alpha percpu	2009-04-10 21:36:18 +02:00
asm-h8300
asm-m32r	Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-04-05 11:04:19 -07:00
crypto
drm	drm: remove unused "can_grow" parameter from drm_crtc_helper_initial_config	2009-04-03 10:21:44 +10:00
keys
linux	net: Avoid extra wakeups of threads blocked in wait_for_packet()	2009-04-28 02:24:21 -07:00
math-emu
media	V4L/DVB (11381): ivtv/cx18: remove VIDIOC_INT_S_AUDIO_ROUTING debug support.	2009-04-06 21:44:28 -03:00
mtd
net	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-2.6	2009-04-16 16:32:29 -07:00
pcmcia
rdma
rxrpc
scsi	PM/Hibernate: Wait for SCSI devices scan to complete during resume	2009-04-13 11:37:07 -07:00
sound
trace	tracing/syscalls: use a dedicated file header	2009-04-09 05:43:32 +02:00
video	tdfxfb: move I2C functionality into the tdfxfb	2009-04-07 08:31:08 -07:00
xen
Kbuild