| Message ID | 20240205210453.11301-4-jdamato@fastly.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Per epoll context busy poll support | expand |
On Mon, 5 Feb 2024 21:04:48 +0000 Joe Damato wrote: > 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. Reviewed-by: Jakub Kicinski <kuba@kernel.org>
On Wed, Feb 7, 2024 at 8:04 PM Jakub Kicinski <kuba@kernel.org> wrote: > > On Mon, 5 Feb 2024 21:04:48 +0000 Joe Damato wrote: > > 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. > > Reviewed-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3985434df527..a69ee11682b9 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -231,6 +231,7 @@ struct eventpoll { u64 busy_poll_usecs; /* busy poll packet budget */ u16 busy_poll_budget; + bool prefer_busy_poll; #endif #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -440,13 +441,14 @@ 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; /* @@ -2105,6 +2107,7 @@ 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);
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> --- fs/eventpoll.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)