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authorDavidlohr Bueso <dave@stgolabs.net>2019-01-03 15:27:02 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-04 13:13:46 -0800
commit74bdc129850c32eaddc625ce557da560303fbf25 (patch)
tree20b4654a2ec7b6e83a7a4bdc0c85f9f07fba2798
parent77b8c0a8e47484e205b01dfedcd224770aa9d800 (diff)
fs/epoll: remove max_nests argument from ep_call_nested()
Patch series "epoll: some miscellaneous optimizations". The following are some incremental optimizations on some of the epoll core. Each patch has the details, but together, the series is seen to shave off measurable cycles on a number of systems and workloads. For example, on a 40-core IB, a pipetest as well as parallel epoll_wait() benchmark show around a 20-30% increase in raw operations per second when the box is fully occupied (incremental thread counts), and up to 15% performance improvement with lower counts. Passes ltp epoll related testcases. This patch(of 6): All callers pass the EP_MAX_NESTS constant already, so lets simplify this a tad and get rid of the redundant parameter for nested eventpolls. Link: http://lkml.kernel.org/r/20181108051006.18751-2-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jason Baron <jbaron@akamai.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/eventpoll.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8a5a1010886b..be50799737f4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -471,7 +471,6 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
* no re-entered.
*
* @ncalls: Pointer to the nested_calls structure to be used for this call.
- * @max_nests: Maximum number of allowed nesting calls.
* @nproc: Nested call core function pointer.
* @priv: Opaque data to be passed to the @nproc callback.
* @cookie: Cookie to be used to identify this nested call.
@@ -480,7 +479,7 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
* Returns: Returns the code returned by the @nproc callback, or -1 if
* the maximum recursion limit has been exceeded.
*/
-static int ep_call_nested(struct nested_calls *ncalls, int max_nests,
+static int ep_call_nested(struct nested_calls *ncalls,
int (*nproc)(void *, void *, int), void *priv,
void *cookie, void *ctx)
{
@@ -499,7 +498,7 @@ static int ep_call_nested(struct nested_calls *ncalls, int max_nests,
*/
list_for_each_entry(tncur, lsthead, llink) {
if (tncur->ctx == ctx &&
- (tncur->cookie == cookie || ++call_nests > max_nests)) {
+ (tncur->cookie == cookie || ++call_nests > EP_MAX_NESTS)) {
/*
* Ops ... loop detected or maximum nest level reached.
* We abort this wake by breaking the cycle itself.
@@ -573,7 +572,7 @@ static void ep_poll_safewake(wait_queue_head_t *wq)
{
int this_cpu = get_cpu();
- ep_call_nested(&poll_safewake_ncalls, EP_MAX_NESTS,
+ ep_call_nested(&poll_safewake_ncalls,
ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu);
put_cpu();
@@ -1333,7 +1332,6 @@ static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)
}
} else {
error = ep_call_nested(&poll_loop_ncalls,
- EP_MAX_NESTS,
reverse_path_check_proc,
child_file, child_file,
current);
@@ -1367,7 +1365,7 @@ static int reverse_path_check(void)
/* let's call this for all tfiles */
list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {
path_count_init();
- error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
+ error = ep_call_nested(&poll_loop_ncalls,
reverse_path_check_proc, current_file,
current_file, current);
if (error)
@@ -1876,7 +1874,7 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
ep_tovisit = epi->ffd.file->private_data;
if (ep_tovisit->visited)
continue;
- error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
+ error = ep_call_nested(&poll_loop_ncalls,
ep_loop_check_proc, epi->ffd.file,
ep_tovisit, current);
if (error != 0)
@@ -1916,7 +1914,7 @@ static int ep_loop_check(struct eventpoll *ep, struct file *file)
int ret;
struct eventpoll *ep_cur, *ep_next;
- ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
+ ret = ep_call_nested(&poll_loop_ncalls,
ep_loop_check_proc, file, ep, current);
/* clear visited list */
list_for_each_entry_safe(ep_cur, ep_next, &visited_list,