kernel: implement separate wait queues for page allocation

give kernel processes and local disk file servers (procs
having noswap flag set) a clear advantage for page allocation
under starved condition by giving them ther own wait queue so
they get readied as soon as pages become available.

1 files changed, 8 insertions, 2 deletions

diff --git a/sys/src/9/port/portdat.h b/sys/src/9/port/portdat.h
index 81bafa4f8..f7501fedc 100644
--- a/sys/src/9/port/portdat.h
+++ b/sys/src/9/port/portdat.h
@@ -34,6 +34,7 @@ typedef struct QLock	QLock;
 typedef struct Queue	Queue;
 typedef struct Ref	Ref;
 typedef struct Rendez	Rendez;
+typedef struct Rendezq	Rendezq;
 typedef struct Rgrp	Rgrp;
 typedef struct RWlock	RWlock;
 typedef struct Sargs	Sargs;
@@ -77,6 +78,12 @@ struct QLock
 	int	locked;		/* flag */
 };
 
+struct Rendezq
+{
+	QLock;
+	Rendez;
+};
+
 struct RWlock
 {
 	Lock	use;
@@ -506,8 +513,7 @@ struct Palloc
 	ulong	freecount;		/* how many pages on free list now */
 	Page	*pages;			/* array of all pages */
 	ulong	user;			/* how many user pages */
-	Rendez	r;			/* Sleep for free mem */
-	QLock	pwait;			/* Queue of procs waiting for memory */
+	Rendezq		pwait[2];	/* Queues of procs waiting for memory */
 	Pallocmem	mem[16];	/* physical user page banks */
 };