signalfd: retrieve multiple signals with one read() call
signalfd: retrieve multiple signals with one read() call

Gathering signals in bulk enables server applications to drain a signal
queue (almost full of realtime signals) more efficiently by reducing the
syscall and file look-up overhead.

Very similar to the sigtimedwait4() call described by Niels Provos, Chuck
Lever, and Stephen Tweedie in a paper entitled "Analyzing the Overload
Behavior of a Simple Web Server".  The paper lists more details and
advantages.

Signed-off-by: Davi E. M. Arnaut <a02bf04bbb18a4f43b21f4f64c342a6586da7a0b@haxent.com.br>
Acked-by: Davide Libenzi <91df8000b8dca80eb036dde93edf593d4a91414e@xmailserver.org>
Cc: Oleg Nesterov <20b70f0af00562e63758b9ee42012ecc96c58590@tv-sign.ru>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas