diff mbox series

[net-next,v8,3/4] eventpoll: Add per-epoll prefer busy poll option

Message ID 20240213061652.6342-4-jdamato@fastly.com (mailing list archive)
State Accepted
Commit de57a251082211b68e8c01e0e8210a23c022ac57
Delegated to: Netdev Maintainers
Headers show
Series Per epoll context busy poll support | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 994 this patch: 994
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 1007 this patch: 1007
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1012 this patch: 1012
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 30 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-02-14--09-00 (tests: 1438)

Commit Message

Joe Damato Feb. 13, 2024, 6:16 a.m. UTC 
When using epoll-based busy poll, the prefer_busy_poll option is hardcoded
to false. Users may want to enable prefer_busy_poll to be used in
conjunction with gro_flush_timeout and defer_hard_irqs_count to keep device
IRQs masked.

Other busy poll methods allow enabling or disabling prefer busy poll via
SO_PREFER_BUSY_POLL, but epoll-based busy polling uses a hardcoded value.

Fix this edge case by adding support for a per-epoll context
prefer_busy_poll option. The default is false, as it was hardcoded before
this change.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 fs/eventpoll.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index ed83ae33dd45..1b8d01af0c2c 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -231,6 +231,7 @@  struct eventpoll {
 	u32 busy_poll_usecs;
 	/* busy poll packet budget */
 	u16 busy_poll_budget;
+	bool prefer_busy_poll;
 #endif
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -438,13 +439,14 @@  static bool ep_busy_loop(struct eventpoll *ep, int nonblock)
 {
 	unsigned int napi_id = READ_ONCE(ep->napi_id);
 	u16 budget = READ_ONCE(ep->busy_poll_budget);
+	bool prefer_busy_poll = READ_ONCE(ep->prefer_busy_poll);
 
 	if (!budget)
 		budget = BUSY_POLL_BUDGET;
 
 	if (napi_id >= MIN_NAPI_ID && ep_busy_loop_on(ep)) {
-		napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false,
-			       budget);
+		napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end,
+			       ep, prefer_busy_poll, budget);
 		if (ep_events_available(ep))
 			return true;
 		/*
@@ -2098,6 +2100,7 @@  static int do_epoll_create(int flags)
 #ifdef CONFIG_NET_RX_BUSY_POLL
 	ep->busy_poll_usecs = 0;
 	ep->busy_poll_budget = 0;
+	ep->prefer_busy_poll = false;
 #endif
 	ep->file = file;
 	fd_install(fd, file);