Björn Töpel 7fd3253a7d net: Introduce preferred busy-polling ... The existing busy-polling mode, enabled by the SO_BUSY_POLL socket option or system-wide using the /proc/sys/net/core/busy_read knob, is an opportunistic. That means that if the NAPI context is not scheduled, it will poll it. If, after busy-polling, the budget is exceeded the busy-polling logic will schedule the NAPI onto the regular softirq handling. One implication of the behavior above is that a busy/heavy loaded NAPI context will never enter/allow for busy-polling. Some applications prefer that most NAPI processing would be done by busy-polling. This series adds a new socket option, SO_PREFER_BUSY_POLL, that works in concert with the napi_defer_hard_irqs and gro_flush_timeout knobs. The napi_defer_hard_irqs and gro_flush_timeout knobs were introduced in commit 6f8b12d661 ("net: napi: add hard irqs deferral feature"), and allows for a user to defer interrupts to be enabled and instead schedule the NAPI context from a watchdog timer. When a user enables the SO_PREFER_BUSY_POLL, again with the other knobs enabled, and the NAPI context is being processed by a softirq, the softirq NAPI processing will exit early to allow the busy-polling to be performed. If the application stops performing busy-polling via a system call, the watchdog timer defined by gro_flush_timeout will timeout, and regular softirq handling will resume. In summary; Heavy traffic applications that prefer busy-polling over softirq processing should use this option. Example usage: $ echo 2 | sudo tee /sys/class/net/ens785f1/napi_defer_hard_irqs $ echo 200000 | sudo tee /sys/class/net/ens785f1/gro_flush_timeout Note that the timeout should be larger than the userspace processing window, otherwise the watchdog will timeout and fall back to regular softirq processing. Enable the SO_BUSY_POLL/SO_PREFER_BUSY_POLL options on your socket. Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/bpf/20201130185205.196029-2-bjorn.topel@gmail.com		2020-12-01 00:09:25 +01:00
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boot	alpha: Replace strncmp with str_has_prefix	2020-06-12 17:43:17 -07:00
configs	Char/Misc driver patches for 5.7-rc1	2020-04-03 13:22:40 -07:00
include	net: Introduce preferred busy-polling	2020-12-01 00:09:25 +01:00
kernel	arch-cleanup-2020-10-22	2020-10-23 10:06:38 -07:00
lib	alpha: propagate the calling convention changes down to csum_partial_copy.c helpers	2020-08-20 15:45:16 -04:00
math-emu	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
mm	mm/alpha: use general page fault accounting	2020-08-12 10:58:03 -07:00
oprofile	smp: Remove smp_call_function() and on_each_cpu() return values	2019-06-23 14:26:26 +02:00
Kconfig	uaccess: add infrastructure for kernel builds with set_fs()	2020-09-08 22:21:32 -04:00
Kconfig.debug	treewide: replace '---help---' in Kconfig files with 'help'	2020-06-14 01:57:21 +09:00
Makefile	kconfig: make arch/*/configs/defconfig the default of KBUILD_DEFCONFIG	2019-06-09 15:08:18 +09:00