From 7d5f466812b3bc87752ede825ee9d94df730ca54 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Wed, 17 Jun 2015 16:47:21 +0200
Subject: erts: Refactor growth of fd tables

to have one common implementation for both _kp and _nkp.
---
 erts/emulator/sys/common/erl_check_io.c | 17 ++++++------
 erts/emulator/sys/common/erl_poll.c     | 49 +++++++++++++++++----------------
 erts/emulator/sys/common/erl_poll.h     |  2 +-
 3 files changed, 36 insertions(+), 32 deletions(-)

(limited to 'erts/emulator/sys')

diff --git a/erts/emulator/sys/common/erl_check_io.c b/erts/emulator/sys/common/erl_check_io.c
index d1d6696090..3097f7b7dd 100644
--- a/erts/emulator/sys/common/erl_check_io.c
+++ b/erts/emulator/sys/common/erl_check_io.c
@@ -41,8 +41,7 @@
 #define ERTS_WANT_TIMER_WHEEL_API
 #include "erl_time.h"
 
-#ifdef ERTS_SYS_CONTINOUS_FD_NUMBERS
-#else
+#ifndef ERTS_SYS_CONTINOUS_FD_NUMBERS
 #  include "safe_hash.h"
 #  define DRV_EV_STATE_HTAB_SIZE 1024
 #endif
@@ -413,14 +412,16 @@ static void
 grow_drv_ev_state(int min_ix)
 {
     int i;
+    int old_len;
     int new_len;
 
-    new_len = ERTS_POLL_EXPORT(erts_poll_get_table_len)(min_ix + 1);
-    if (new_len > max_fds)
-	new_len = max_fds;
-
     erts_smp_mtx_lock(&drv_ev_state_grow_lock);
-    if (erts_smp_atomic_read_nob(&drv_ev_state_len) <= min_ix) {
+    old_len = erts_smp_atomic_read_nob(&drv_ev_state_len);
+    if (min_ix >= old_len) {
+        new_len = erts_poll_new_table_len(old_len, min_ix + 1);
+        if (new_len > max_fds)
+            new_len = max_fds;
+
 	for (i=0; i<DRV_EV_STATE_LOCK_CNT; i++) { /* lock all fd's */
 	    erts_smp_mtx_lock(&drv_ev_state_locks[i].lck);
 	}
@@ -430,7 +431,7 @@ grow_drv_ev_state(int min_ix)
 				       sizeof(ErtsDrvEventState)*new_len)
 			: erts_alloc(ERTS_ALC_T_DRV_EV_STATE,
 				     sizeof(ErtsDrvEventState)*new_len));
-	for (i = erts_smp_atomic_read_nob(&drv_ev_state_len); i < new_len; i++) {
+	for (i = old_len; i < new_len; i++) {
 	    drv_ev_state[i].fd = (ErtsSysFdType) i;
 	    drv_ev_state[i].driver.select = NULL;
 #if ERTS_CIO_HAVE_DRV_EVENT
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index 71c4239902..68d3c30bd4 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -153,9 +153,6 @@ int ERTS_SELECT(int nfds, ERTS_fd_set *readfds, ERTS_fd_set *writefds,
 
 #define ERTS_POLL_COALESCE_KP_RES (ERTS_POLL_USE_KQUEUE || ERTS_POLL_USE_EPOLL)
 
-#define ERTS_EV_TABLE_MIN_LENGTH		1024
-#define ERTS_EV_TABLE_EXP_THRESHOLD		(2048*1024)
-
 #ifdef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT
 #  define ERTS_POLL_ASYNC_INTERRUPT_SUPPORT 1
 #else
@@ -703,27 +700,33 @@ free_update_requests_block(ErtsPollSet ps,
  * --- Growing poll set structures -------------------------------------------
  */
 
-int
-ERTS_POLL_EXPORT(erts_poll_get_table_len) (int new_len)
+#ifndef ERTS_KERNEL_POLL_VERSION   /* only one shared implementation */
+
+#define ERTS_FD_TABLE_MIN_LENGTH	1024
+#define ERTS_FD_TABLE_EXP_THRESHOLD	(2048*1024)
+
+int erts_poll_new_table_len (int old_len, int need_len)
 {
-    if (new_len < ERTS_EV_TABLE_MIN_LENGTH) {
-	new_len = ERTS_EV_TABLE_MIN_LENGTH;
-    } else if (new_len < ERTS_EV_TABLE_EXP_THRESHOLD) {
-	/* find next power of 2 */
-	--new_len;
-	new_len |= new_len >> 1;
-	new_len |= new_len >> 2;
-	new_len |= new_len >> 4;
-	new_len |= new_len >> 8;
-	new_len |= new_len >> 16;
-	++new_len;
-    } else {
-	/* grow incrementally */
-	new_len += ERTS_EV_TABLE_EXP_THRESHOLD;
+    int new_len;
+
+    ASSERT(need_len > old_len);
+    if (need_len < ERTS_FD_TABLE_MIN_LENGTH) {
+	new_len = ERTS_FD_TABLE_MIN_LENGTH;
     }
+    else {
+        new_len = old_len;
+        do {            
+            if (new_len < ERTS_FD_TABLE_EXP_THRESHOLD)
+                new_len *= 2;
+            else
+                new_len += ERTS_FD_TABLE_EXP_THRESHOLD;
+
+        } while (new_len < need_len);
+    }
+    ASSERT(new_len >= need_len);
     return new_len;
 }
-
+#endif
 
 #if ERTS_POLL_USE_KERNEL_POLL
 static void
@@ -737,7 +740,7 @@ grow_res_events(ErtsPollSet ps, int new_len)
 #elif ERTS_POLL_USE_KQUEUE
 	struct kevent
 #endif
-	) * ERTS_POLL_EXPORT(erts_poll_get_table_len)(new_len);
+	) * erts_poll_new_table_len(ps->res_events_len, new_len);
     /* We do not need to save previously stored data */
     if (ps->res_events)
 	erts_free(ERTS_ALC_T_POLL_RES_EVS, ps->res_events);
@@ -751,7 +754,7 @@ static void
 grow_poll_fds(ErtsPollSet ps, int min_ix)
 {
     int i;
-    int new_len = ERTS_POLL_EXPORT(erts_poll_get_table_len)(min_ix + 1);
+    int new_len = erts_poll_new_table_len(ps->poll_fds_len, min_ix + 1);
     if (new_len > max_fds)
 	new_len = max_fds;
     ps->poll_fds = (ps->poll_fds_len
@@ -800,7 +803,7 @@ static void
 grow_fds_status(ErtsPollSet ps, int min_fd)
 {
     int i;
-    int new_len = ERTS_POLL_EXPORT(erts_poll_get_table_len)(min_fd + 1);
+    int new_len = erts_poll_new_table_len(ps->fds_status_len, min_fd + 1);
     ASSERT(min_fd < max_fds);
     if (new_len > max_fds)
 	new_len = max_fds;
diff --git a/erts/emulator/sys/common/erl_poll.h b/erts/emulator/sys/common/erl_poll.h
index ae2d063805..ad8f714d6e 100644
--- a/erts/emulator/sys/common/erl_poll.h
+++ b/erts/emulator/sys/common/erl_poll.h
@@ -275,6 +275,6 @@ void		ERTS_POLL_EXPORT(erts_poll_get_selected_events)(ErtsPollSet,
 								ErtsPollEvents [],
 								int);
 
-int		ERTS_POLL_EXPORT(erts_poll_get_table_len)(int);
+int erts_poll_new_table_len(int old_len, int need_len);
 
 #endif /* #ifndef ERL_POLL_H__ */
-- 
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