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eventpoll: support busy poll per epoll instance
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 <jdamato@fastly.com> Acked-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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723615a14b
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85455c795c
1 changed files with 39 additions and 5 deletions
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@ -227,6 +227,8 @@ struct eventpoll {
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#ifdef CONFIG_NET_RX_BUSY_POLL
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#ifdef CONFIG_NET_RX_BUSY_POLL
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/* used to track busy poll napi_id */
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/* used to track busy poll napi_id */
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unsigned int napi_id;
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unsigned int napi_id;
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/* busy poll timeout */
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u32 busy_poll_usecs;
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#endif
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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@ -387,11 +389,41 @@ static inline int ep_events_available(struct eventpoll *ep)
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}
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}
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#ifdef CONFIG_NET_RX_BUSY_POLL
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#ifdef CONFIG_NET_RX_BUSY_POLL
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/**
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* busy_loop_ep_timeout - check if busy poll has timed out. The timeout value
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* from the epoll instance ep is preferred, but if it is not set fallback to
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* the system-wide global via busy_loop_timeout.
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*
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* @start_time: The start time used to compute the remaining time until timeout.
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* @ep: Pointer to the eventpoll context.
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*
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* Return: true if the timeout has expired, false otherwise.
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*/
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static bool busy_loop_ep_timeout(unsigned long start_time,
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struct eventpoll *ep)
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{
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unsigned long bp_usec = READ_ONCE(ep->busy_poll_usecs);
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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return time_after(now, end_time);
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} else {
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return busy_loop_timeout(start_time);
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}
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}
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static bool ep_busy_loop_on(struct eventpoll *ep)
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{
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return !!ep->busy_poll_usecs || net_busy_loop_on();
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}
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static bool ep_busy_loop_end(void *p, unsigned long start_time)
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static bool ep_busy_loop_end(void *p, unsigned long start_time)
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{
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{
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struct eventpoll *ep = p;
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struct eventpoll *ep = p;
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return ep_events_available(ep) || busy_loop_timeout(start_time);
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return ep_events_available(ep) || busy_loop_ep_timeout(start_time, ep);
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}
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}
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/*
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/*
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@ -404,7 +436,7 @@ static bool ep_busy_loop(struct eventpoll *ep, int nonblock)
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{
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{
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unsigned int napi_id = READ_ONCE(ep->napi_id);
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unsigned int napi_id = READ_ONCE(ep->napi_id);
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if ((napi_id >= MIN_NAPI_ID) && net_busy_loop_on()) {
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if (napi_id >= MIN_NAPI_ID && ep_busy_loop_on(ep)) {
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napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false,
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napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false,
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BUSY_POLL_BUDGET);
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BUSY_POLL_BUDGET);
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if (ep_events_available(ep))
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if (ep_events_available(ep))
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@ -425,12 +457,12 @@ static bool ep_busy_loop(struct eventpoll *ep, int nonblock)
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*/
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*/
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static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
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static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
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{
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{
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struct eventpoll *ep;
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struct eventpoll *ep = epi->ep;
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unsigned int napi_id;
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unsigned int napi_id;
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struct socket *sock;
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struct socket *sock;
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struct sock *sk;
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struct sock *sk;
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if (!net_busy_loop_on())
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if (!ep_busy_loop_on(ep))
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return;
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return;
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sock = sock_from_file(epi->ffd.file);
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sock = sock_from_file(epi->ffd.file);
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@ -442,7 +474,6 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
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return;
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return;
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napi_id = READ_ONCE(sk->sk_napi_id);
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napi_id = READ_ONCE(sk->sk_napi_id);
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ep = epi->ep;
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/* Non-NAPI IDs can be rejected
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/* Non-NAPI IDs can be rejected
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* or
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* or
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@ -2058,6 +2089,9 @@ static int do_epoll_create(int flags)
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error = PTR_ERR(file);
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error = PTR_ERR(file);
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goto out_free_fd;
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goto out_free_fd;
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}
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}
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#ifdef CONFIG_NET_RX_BUSY_POLL
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ep->busy_poll_usecs = 0;
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#endif
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ep->file = file;
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ep->file = file;
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fd_install(fd, file);
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fd_install(fd, file);
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return fd;
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return fd;
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