From 29f60cace1a71edd730c60ddac8dfbd962741038 Mon Sep 17 00:00:00 2001 From: cinap_lenrek Date: Tue, 22 Dec 2020 16:29:55 +0100 Subject: kernel: avoid palloc lock during mmurelease() Previously, mmurelease() was always called with palloc spinlock held. This is unneccesary for some mmurelease() implementations as they wont release pages to the palloc pool. This change removes pagechainhead() and pagechaindone() and replaces them with just freepages() call, which aquires the palloc lock internally as needed. freepages() avoids holding the palloc lock while walking the linked list of pages, avoding some lock contention. --- sys/src/9/port/devsegment.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'sys/src/9/port/devsegment.c') diff --git a/sys/src/9/port/devsegment.c b/sys/src/9/port/devsegment.c index fcaf8f3e4..dfbd34fbf 100644 --- a/sys/src/9/port/devsegment.c +++ b/sys/src/9/port/devsegment.c @@ -469,7 +469,7 @@ fixedseg(uintptr va, ulong len) { KMap *k; Segment *s; - Page **f, *p, *l, *h; + Page **f, *p, *l, *h, *t; ulong n, i; int color; @@ -492,12 +492,13 @@ fixedseg(uintptr va, ulong len) continue; i = 0; - h = nil; + h = t = nil; f = &palloc.head; while((p = *f) != nil){ if(p > &l[-len] && p <= l){ *f = p->next; - p->next = h; + if((p->next = h) == nil) + t = p; h = p; if(++i < len) continue; @@ -505,15 +506,15 @@ fixedseg(uintptr va, ulong len) } f = &p->next; } - palloc.freecount -= i; if(i != len){ - while((p = h) != nil){ - h = h->next; - pagechainhead(p); + if(h != nil){ + t->next = palloc.head; + palloc.head = h; } goto Retry; } + palloc.freecount -= i; unlock(&palloc); p = &l[-len]; -- cgit v1.2.3