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charset="utf-8" Allow busy polling on a per-epoll context basis. The per-epoll context usec timeout value is preferred, but the pre-existing system wide sysctl value is still supported if it specified. busy_poll_usecs is a u32, but in a follow up patch the ioctl provided to the user only allows setting a value from 0 to S32_MAX. Signed-off-by: Joe Damato Acked-by: Stanislav Fomichev Reviewed-by: Eric Dumazet --- fs/eventpoll.c | 44 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 5 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3534d36a1474..401f865eced9 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -227,6 +227,8 @@ struct eventpoll { #ifdef CONFIG_NET_RX_BUSY_POLL /* used to track busy poll napi_id */ unsigned int napi_id; + /* busy poll timeout */ + u32 busy_poll_usecs; #endif =20 #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -387,11 +389,41 @@ static inline int ep_events_available(struct eventpol= l *ep) } =20 #ifdef CONFIG_NET_RX_BUSY_POLL +/** + * busy_loop_ep_timeout - check if busy poll has timed out. The timeout va= lue + * from the epoll instance ep is preferred, but if it is not set fallback = to + * the system-wide global via busy_loop_timeout. + * + * @start_time: The start time used to compute the remaining time until ti= meout. + * @ep: Pointer to the eventpoll context. + * + * Return: true if the timeout has expired, false otherwise. + */ +static bool busy_loop_ep_timeout(unsigned long start_time, + struct eventpoll *ep) +{ + unsigned long bp_usec =3D READ_ONCE(ep->busy_poll_usecs); + + if (bp_usec) { + unsigned long end_time =3D start_time + bp_usec; + unsigned long now =3D busy_loop_current_time(); + + return time_after(now, end_time); + } else { + return busy_loop_timeout(start_time); + } +} + +static bool ep_busy_loop_on(struct eventpoll *ep) +{ + return !!ep->busy_poll_usecs || net_busy_loop_on(); +} + static bool ep_busy_loop_end(void *p, unsigned long start_time) { struct eventpoll *ep =3D p; =20 - return ep_events_available(ep) || busy_loop_timeout(start_time); + return ep_events_available(ep) || busy_loop_ep_timeout(start_time, ep); } =20 /* @@ -404,7 +436,7 @@ static bool ep_busy_loop(struct eventpoll *ep, int nonb= lock) { unsigned int napi_id =3D READ_ONCE(ep->napi_id); =20 - if ((napi_id >=3D MIN_NAPI_ID) && net_busy_loop_on()) { + if (napi_id >=3D MIN_NAPI_ID && ep_busy_loop_on(ep)) { napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false, BUSY_POLL_BUDGET); if (ep_events_available(ep)) @@ -425,12 +457,12 @@ static bool ep_busy_loop(struct eventpoll *ep, int no= nblock) */ static inline void ep_set_busy_poll_napi_id(struct epitem *epi) { - struct eventpoll *ep; + struct eventpoll *ep =3D epi->ep; unsigned int napi_id; struct socket *sock; struct sock *sk; =20 - if (!net_busy_loop_on()) + if (!ep_busy_loop_on(ep)) return; =20 sock =3D sock_from_file(epi->ffd.file); @@ -442,7 +474,6 @@ static inline void ep_set_busy_poll_napi_id(struct epit= em *epi) return; =20 napi_id =3D READ_ONCE(sk->sk_napi_id); - ep =3D epi->ep; =20 /* Non-NAPI IDs can be rejected * or @@ -2058,6 +2089,9 @@ static int do_epoll_create(int flags) error =3D PTR_ERR(file); goto out_free_fd; } +#ifdef CONFIG_NET_RX_BUSY_POLL + ep->busy_poll_usecs =3D 0; +#endif ep->file =3D file; fd_install(fd, file); return fd; --=20 2.25.1