diff options
Diffstat (limited to 'fs/select.c')
| -rw-r--r-- | fs/select.c | 47 |
1 files changed, 44 insertions, 3 deletions
diff --git a/fs/select.c b/fs/select.c index e56560d2b08a..64c2404f2cc0 100644 --- a/fs/select.c +++ b/fs/select.c @@ -26,6 +26,7 @@ #include <linux/fs.h> #include <linux/rcupdate.h> #include <linux/hrtimer.h> +#include <trace/fs.h> #include <asm/uaccess.h> @@ -98,6 +99,9 @@ struct poll_table_page { #define POLL_TABLE_FULL(table) \ ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) +DEFINE_TRACE(fs_select); +DEFINE_TRACE(fs_poll); + /* * Ok, Peter made a complicated, but straightforward multiple_wait() function. * I have rewritten this, taking some shortcuts: This code may not be easy to @@ -112,6 +116,9 @@ struct poll_table_page { */ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p); +static void __pollwait_exclusive(struct file *filp, + wait_queue_head_t *wait_address, + poll_table *p); void poll_initwait(struct poll_wqueues *pwq) { @@ -152,6 +159,20 @@ void poll_freewait(struct poll_wqueues *pwq) } EXPORT_SYMBOL(poll_freewait); +/** + * poll_wait_set_exclusive - set poll wait queue to exclusive + * + * Sets up a poll wait queue to use exclusive wakeups. This is useful to + * wake up only one waiter at each wakeup. Used to work-around "thundering herd" + * problem. + */ +void poll_wait_set_exclusive(poll_table *p) +{ + if (p) + init_poll_funcptr(p, __pollwait_exclusive); +} +EXPORT_SYMBOL(poll_wait_set_exclusive); + static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p) { struct poll_table_page *table = p->table; @@ -213,8 +234,10 @@ static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key) } /* Add a new entry */ -static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, - poll_table *p) +static void __pollwait_common(struct file *filp, + wait_queue_head_t *wait_address, + poll_table *p, + int exclusive) { struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt); struct poll_table_entry *entry = poll_get_entry(pwq); @@ -226,7 +249,23 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, entry->key = p->key; init_waitqueue_func_entry(&entry->wait, pollwake); entry->wait.private = pwq; - add_wait_queue(wait_address, &entry->wait); + if (!exclusive) + add_wait_queue(wait_address, &entry->wait); + else + add_wait_queue_exclusive(wait_address, &entry->wait); +} + +static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, + poll_table *p) +{ + __pollwait_common(filp, wait_address, p, 0); +} + +static void __pollwait_exclusive(struct file *filp, + wait_queue_head_t *wait_address, + poll_table *p) +{ + __pollwait_common(filp, wait_address, p, 1); } int poll_schedule_timeout(struct poll_wqueues *pwq, int state, @@ -450,6 +489,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) file = fget_light(i, &fput_needed); if (file) { f_op = file->f_op; + trace_fs_select(i, end_time); mask = DEFAULT_POLLMASK; if (f_op && f_op->poll) { wait_key_set(wait, in, out, bit); @@ -739,6 +779,7 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) file = fget_light(fd, &fput_needed); mask = POLLNVAL; if (file != NULL) { + trace_fs_poll(fd); mask = DEFAULT_POLLMASK; if (file->f_op && file->f_op->poll) { if (pwait) |