git: 10fe9a1fb4df - main - busdma_bounce: Make the map waiting list per-bounce-zone.

The branch main has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=10fe9a1fb4df5a55e3dae6017034f48a4ff02045

commit 10fe9a1fb4df5a55e3dae6017034f48a4ff02045
Author:     John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2022-04-21 17:41:09 +0000
Commit:     John Baldwin <jhb@FreeBSD.org>
CommitDate: 2022-04-21 17:41:09 +0000

    busdma_bounce: Make the map waiting list per-bounce-zone.
    
    When pages are freed to a bounce zone, only maps waiting for pages for
    that zone can make forward progress.  If a map for a different bounce
    zone is at the head of the global list, then requests that could
    otherwise make forward progress will be stalled waiting on the other
    bounce zone.  If bounce zones shared bounce pages then a global list
    would still make sense to prevent "later" requests from starving an
    earlier request but that is not a concern with per-zone bounce page
    pools.
    
    Reviewed by:    imp
    Sponsored by:   Netflix
    Differential Revision:  https://reviews.freebsd.org/D34966
---
 sys/kern/subr_busdma_bounce.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sys/kern/subr_busdma_bounce.c b/sys/kern/subr_busdma_bounce.c
index 2c5cc1ea83a2..586998e01673 100644
--- a/sys/kern/subr_busdma_bounce.c
+++ b/sys/kern/subr_busdma_bounce.c
@@ -65,6 +65,7 @@ struct bounce_page {
 struct bounce_zone {
 	STAILQ_ENTRY(bounce_zone) links;
 	STAILQ_HEAD(, bounce_page) bounce_page_list;
+	STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 	int		total_bpages;
 	int		free_bpages;
 	int		reserved_bpages;
@@ -88,7 +89,6 @@ static int total_bpages;
 static int busdma_zonecount;
 
 static STAILQ_HEAD(, bounce_zone) bounce_zone_list;
-static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
 
 static MALLOC_DEFINE(M_BOUNCE, "bounce", "busdma bounce pages");
@@ -103,6 +103,7 @@ static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
 static int
 _bus_dmamap_reserve_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int flags)
 {
+	struct bounce_zone *bz;
 
 	/* Reserve Necessary Bounce Pages */
 	mtx_lock(&bounce_lock);
@@ -115,7 +116,9 @@ _bus_dmamap_reserve_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int flags)
 	} else {
 		if (reserve_bounce_pages(dmat, map, 1) != 0) {
 			/* Queue us for resources */
-			STAILQ_INSERT_TAIL(&bounce_map_waitinglist, map, links);
+			bz = dmat->bounce_zone;
+			STAILQ_INSERT_TAIL(&bz->bounce_map_waitinglist, map,
+			    links);
 			mtx_unlock(&bounce_lock);
 			return (EINPROGRESS);
 		}
@@ -131,7 +134,6 @@ init_bounce_pages(void *dummy __unused)
 
 	total_bpages = 0;
 	STAILQ_INIT(&bounce_zone_list);
-	STAILQ_INIT(&bounce_map_waitinglist);
 	STAILQ_INIT(&bounce_map_callbacklist);
 	mtx_init(&bounce_lock, "bounce pages lock", NULL, MTX_DEF);
 }
@@ -174,6 +176,7 @@ alloc_bounce_zone(bus_dma_tag_t dmat)
 		return (ENOMEM);
 
 	STAILQ_INIT(&bz->bounce_page_list);
+	STAILQ_INIT(&bz->bounce_map_waitinglist);
 	bz->free_bpages = 0;
 	bz->reserved_bpages = 0;
 	bz->active_bpages = 0;
@@ -403,9 +406,9 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
 	STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
 	bz->free_bpages++;
 	bz->active_bpages--;
-	if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {
+	if ((map = STAILQ_FIRST(&bz->bounce_map_waitinglist)) != NULL) {
 		if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
-			STAILQ_REMOVE_HEAD(&bounce_map_waitinglist, links);
+			STAILQ_REMOVE_HEAD(&bz->bounce_map_waitinglist, links);
 			STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
 			    map, links);
 			bz->total_deferred++;