MINOR: dynbuf: pass offer_buffers() the number of buffers instead of a threshold

Historically this function would try to wake the most accurate number of
process_stream() waiters. But since the introduction of filters which could
also require buffers (e.g. for compression), things started not to be as
accurate anymore. Nowadays muxes and transport layers also use buffers, so
the runqueue size has nothing to do anymore with the number of supposed
users to come.

In addition to this, the threshold was compared to the number of free buffer
calculated as allocated minus used, but this didn't work anymore with local
pools since these counts are not updated upon alloc/free!

Let's clean this up and pass the number of released buffers instead, and
consider that each waiter successfully called counts as one buffer. This
is not rocket science and will not suddenly fix everything, but at least
it cannot be as wrong as it is today.

This could have been marked as a bug given that the current situation is
totally broken regarding this, but this probably doesn't completely fix
it, it only goes in a better direction. It is possible however that it
makes sense in the future to backport this as part of a larger series if
the situation significantly improves.

(cherry picked from commit 4d77bbf8560b5d5b32409be131e4975811bfec28)
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/include/haproxy/channel.h b/include/haproxy/channel.h
index 47e4f44..296e465 100644 (file)
--- a/include/haproxy/channel.h
+++ b/include/haproxy/channel.h
@@ -864,7 +864,7 @@ static inline void channel_release_buffer(struct channel *chn, struct buffer_wai
 {
        if (c_size(chn) && c_empty(chn)) {
                b_free(&chn->buf);
-               offer_buffers(wait->target, tasks_run_queue);
+               offer_buffers(wait->target, 1);
        }
 }
 

diff --git a/include/haproxy/dynbuf.h b/include/haproxy/dynbuf.h
index 83c2a98..c31b83a 100644 (file)
--- a/include/haproxy/dynbuf.h
+++ b/include/haproxy/dynbuf.h
@@ -186,19 +186,19 @@ static inline struct buffer *b_alloc_margin(struct buffer *buf, int margin)
 }
 
 
-/* Offer a buffer currently belonging to target <from> to whoever needs one.
- * Any pointer is valid for <from>, including NULL. Its purpose is to avoid
- * passing a buffer to oneself in case of failed allocations (e.g. need two
- * buffers, get one, fail, release it and wake up self again). In case of
- * normal buffer release where it is expected that the caller is not waiting
+/* Offer one or multiple buffer currently belonging to target <from> to whoever
+ * needs one. Any pointer is valid for <from>, including NULL. Its purpose is
+ * to avoid passing a buffer to oneself in case of failed allocations (e.g.
+ * need two buffers, get one, fail, release it and wake up self again). In case
+ * of normal buffer release where it is expected that the caller is not waiting
  * for a buffer, NULL is fine. It will wake waiters on the current thread only.
  */
-void __offer_buffer(void *from, unsigned int threshold);
+void __offer_buffers(void *from, unsigned int count);
 
-static inline void offer_buffers(void *from, unsigned int threshold)
+static inline void offer_buffers(void *from, unsigned int count)
 {
        if (!LIST_ISEMPTY(&ti->buffer_wq))
-               __offer_buffer(from, threshold);
+               __offer_buffers(from, count);
 }
 
 

diff --git a/src/check.c b/src/check.c
index 7226def..35ecf9e 100644 (file)
--- a/src/check.c
+++ b/src/check.c
@@ -1029,7 +1029,7 @@ void check_release_buf(struct check *check, struct buffer *bptr)
 {
        if (bptr->size) {
                b_free(bptr);
-               offer_buffers(check->buf_wait.target, tasks_run_queue);
+               offer_buffers(check->buf_wait.target, 1);
        }
 }
 

diff --git a/src/dynbuf.c b/src/dynbuf.c
index a6d1d40..8b492e2 100644 (file)
--- a/src/dynbuf.c
+++ b/src/dynbuf.c
@@ -96,32 +96,26 @@ void buffer_dump(FILE *o, struct buffer *b, int from, int to)
        fflush(o);
 }
 
-/* see offer_buffer() for details */
-void __offer_buffer(void *from, unsigned int threshold)
+/* see offer_buffers() for details */
+void __offer_buffers(void *from, unsigned int count)
 {
        struct buffer_wait *wait, *wait_back;
-       int avail;
 
        /* For now, we consider that all objects need 1 buffer, so we can stop
         * waking up them once we have enough of them to eat all the available
         * buffers. Note that we don't really know if they are streams or just
         * other tasks, but that's a rough estimate. Similarly, for each cached
-        * event we'll need 1 buffer. If no buffer is currently used, always
-        * wake up the number of tasks we can offer a buffer based on what is
-        * allocated, and in any case at least one task per two reserved
-        * buffers.
+        * event we'll need 1 buffer.
         */
-       avail = pool_head_buffer->allocated - pool_head_buffer->used - global.tune.reserved_bufs / 2;
-
        list_for_each_entry_safe(wait, wait_back, &ti->buffer_wq, list) {
-               if (avail <= threshold)
+               if (!count)
                        break;
 
                if (wait->target == from || !wait->wakeup_cb(wait->target))
                        continue;
 
                LIST_DEL_INIT(&wait->list);
-               avail--;
+               count--;
        }
 }
 

diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index f756609..2accd8b 100644 (file)
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -2853,7 +2853,7 @@ spoe_release_buffer(struct buffer *buf, struct buffer_wait *buffer_wait)
        /* Release the buffer if needed */
        if (buf->size) {
                b_free(buf);
-               offer_buffers(buffer_wait->target, tasks_run_queue);
+               offer_buffers(buffer_wait->target, 1);
        }
 }
 

diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index 855cb5a..837c894 100644 (file)
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -615,7 +615,7 @@ static inline void fcgi_release_buf(struct fcgi_conn *fconn, struct buffer *bptr
 {
        if (bptr->size) {
                b_free(bptr);
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, 1);
        }
 }
 
@@ -629,7 +629,7 @@ static inline void fcgi_release_mbuf(struct fcgi_conn *fconn)
                count++;
        }
        if (count)
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, count);
 }
 
 /* Returns the number of allocatable outgoing streams for the connection taking
@@ -1019,7 +1019,7 @@ static void fcgi_strm_destroy(struct fcgi_strm *fstrm)
        eb32_delete(&fstrm->by_id);
        if (b_size(&fstrm->rxbuf)) {
                b_free(&fstrm->rxbuf);
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, 1);
        }
        if (fstrm->subs)
                fstrm->subs->events = 0;
@@ -2862,7 +2862,7 @@ static int fcgi_send(struct fcgi_conn *fconn)
                }
 
                if (released)
-                       offer_buffers(NULL, tasks_run_queue);
+                       offer_buffers(NULL, released);
 
                /* wrote at least one byte, the buffer is not full anymore */
                if (fconn->flags & (FCGI_CF_MUX_MFULL | FCGI_CF_DEM_MROOM))
@@ -3172,7 +3172,7 @@ do_leave:
                }
 
                if (released)
-                       offer_buffers(NULL, tasks_run_queue);
+                       offer_buffers(NULL, released);
        }
 
   end:

diff --git a/src/mux_h1.c b/src/mux_h1.c
index b2e6ece..f219183 100644 (file)
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -433,7 +433,7 @@ static inline void h1_release_buf(struct h1c *h1c, struct buffer *bptr)
 {
        if (bptr->size) {
                b_free(bptr);
-               offer_buffers(h1c->buf_wait.target, tasks_run_queue);
+               offer_buffers(h1c->buf_wait.target, 1);
        }
 }
 

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 9272ae4..31e6b8c 100644 (file)
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -811,7 +811,7 @@ static inline void h2_release_buf(struct h2c *h2c, struct buffer *bptr)
 {
        if (bptr->size) {
                b_free(bptr);
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, 1);
        }
 }
 
@@ -825,7 +825,7 @@ static inline void h2_release_mbuf(struct h2c *h2c)
                count++;
        }
        if (count)
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, count);
 }
 
 /* returns the number of allocatable outgoing streams for the connection taking
@@ -1385,7 +1385,7 @@ static void h2s_destroy(struct h2s *h2s)
        eb32_delete(&h2s->by_id);
        if (b_size(&h2s->rxbuf)) {
                b_free(&h2s->rxbuf);
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, 1);
        }
 
        if (h2s->subs)
@@ -3672,7 +3672,7 @@ static int h2_send(struct h2c *h2c)
                }
 
                if (released)
-                       offer_buffers(NULL, tasks_run_queue);
+                       offer_buffers(NULL, released);
 
                /* wrote at least one byte, the buffer is not full anymore */
                if (sent)
@@ -3975,7 +3975,7 @@ do_leave:
                }
 
                if (released)
-                       offer_buffers(NULL, tasks_run_queue);
+                       offer_buffers(NULL, released);
        }
 
        /* in any case this connection must not be considered idle anymore */
@@ -6005,7 +6005,7 @@ static size_t h2_rcv_buf(struct conn_stream *cs, struct buffer *buf, size_t coun
                        cs->flags |= CS_FL_ERROR;
                if (b_size(&h2s->rxbuf)) {
                        b_free(&h2s->rxbuf);
-                       offer_buffers(NULL, tasks_run_queue);
+                       offer_buffers(NULL, 1);
                }
        }
 

diff --git a/src/stream.c b/src/stream.c
index 6fca1d1..411849c 100644 (file)
--- a/src/stream.c
+++ b/src/stream.c
@@ -598,9 +598,11 @@ static void stream_free(struct stream *s)
                LIST_DEL_INIT(&s->buffer_wait.list);
 
        if (s->req.buf.size || s->res.buf.size) {
+               int count = !!s->req.buf.size + !!s->res.buf.size;
+
                b_free(&s->req.buf);
                b_free(&s->res.buf);
-               offer_buffers(NULL, tasks_run_queue);
+               offer_buffers(NULL, count);
        }
 
        pool_free(pool_head_uniqueid, s->unique_id.ptr);
@@ -748,11 +750,11 @@ void stream_release_buffers(struct stream *s)
        int offer = 0;
 
        if (c_size(&s->req) && c_empty(&s->req)) {
-               offer = 1;
+               offer++;
                b_free(&s->req.buf);
        }
        if (c_size(&s->res) && c_empty(&s->res)) {
-               offer = 1;
+               offer++;
                b_free(&s->res.buf);
        }
 
@@ -760,7 +762,7 @@ void stream_release_buffers(struct stream *s)
         * someone waiting, we can wake up a waiter and offer them.
         */
        if (offer)
-               offer_buffers(s, tasks_run_queue);
+               offer_buffers(s, offer);
 }
 
 void stream_process_counters(struct stream *s)