Attachment 16051 Details for Bug 15513 – Some minor offscreen area eviction improvements

[patch] Some minor offscreen area eviction improvements

exa-offscreen-eviction.diff (text/plain), 3.94 KB, created by Michel Dänzer on 2008-04-20 03:14:54 UTC

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Creator: Michel Dänzer

Created: 2008-04-20 03:14:54 UTC

Size: 3.94 KB

patch

obsolete

>EXA: Offscreen memory eviction improvements.
>
>From:  <michel@tungstengraphics.com>
>
>
>---
>
> exa/exa.h           |    2 ++
> exa/exa_offscreen.c |   49 ++++++++++++++++++++++++++++++++++---------------
> 2 files changed, 36 insertions(+), 15 deletions(-)
>
>
>diff --git a/exa/exa.h b/exa/exa.h
>index 97ae6c0..2562094 100644
>--- a/exa/exa.h
>+++ b/exa/exa.h
>@@ -64,6 +64,8 @@ struct _ExaOffscreenArea {
>     ExaOffscreenState   state;
> 
>     ExaOffscreenArea    *next;
>+
>+    unsigned            eviction_cost;
> };
> 
> /**
>diff --git a/exa/exa_offscreen.c b/exa/exa_offscreen.c
>index 85b5388..4aaa2c1 100644
>--- a/exa/exa_offscreen.c
>+++ b/exa/exa_offscreen.c
>@@ -21,11 +21,9 @@
>  */
> 
> /** @file
>- * This allocator allocates blocks of memory by maintaining a list of areas
>- * and a score for each area.  As an area is marked used, its score is
>- * incremented, and periodically all of the areas have their scores decayed by
>- * a fraction.  When allocating, the contiguous block of areas with the minimum
>- * score is found and evicted in order to make room for the new allocation.
>+ * This allocator allocates blocks of memory by maintaining a list of areas.
>+ * When allocating, the contiguous block of areas with the minimum eviction
>+ * cost is found and evicted in order to make room for the new allocation.
>  */
> 
> #include "exa_priv.h"
>@@ -71,19 +69,36 @@ ExaOffscreenKickOut (ScreenPtr pScreen, ExaOffscreenArea *area)
>     return exaOffscreenFree (pScreen, area);
> }
> 
>-#define AREA_SCORE(area) (area->size / (double)(pExaScr->offScreenCounter - area->last_use))
>+static void
>+exaUpdateEvictionCost(ExaOffscreenArea *area, unsigned offScreenCounter)
>+{
>+    unsigned age;
>+
>+    if (area->state == ExaOffscreenAvail)
>+	return;
>+
>+    age = offScreenCounter - area->last_use;
>+
>+    /* This is unlikely to happen, but could result in a division by zero... */
>+    if (age > (UINT_MAX / 2)) {
>+	age = UINT_MAX / 2;
>+	area->last_use = offScreenCounter - age;
>+    }
>+
>+    area->eviction_cost = area->size / age;
>+}
> 
> static ExaOffscreenArea *
> exaFindAreaToEvict(ExaScreenPrivPtr pExaScr, int size, int align)
> {
>     ExaOffscreenArea *begin, *end, *best;
>-    double score, best_score;
>+    unsigned cost, best_cost;
>     int avail, real_size, tmp;
> 
>-    best_score = UINT_MAX;
>+    best_cost = UINT_MAX;
>     begin = end = pExaScr->info->offScreenAreas;
>     avail = 0;
>-    score = 0;
>+    cost = 0;
>     best = 0;
> 
>     while (end != NULL)
>@@ -106,23 +121,24 @@ exaFindAreaToEvict(ExaScreenPrivPtr pExaScr, int size, int align)
> 	    if (end->state == ExaOffscreenLocked) {
> 		/* Can't more room here, restart after this locked area */
> 		avail = 0;
>-		score = 0;
>+		cost = 0;
> 		begin = end;
> 		goto restart;
> 	    }
> 	    avail += end->size;
>-	    score += AREA_SCORE(end);
>+	    exaUpdateEvictionCost(end, pExaScr->offScreenCounter);
>+	    cost += end->eviction_cost;
> 	    end = end->next;
> 	}
> 
>-	/* Check the score, update best */
>-	if (avail >= real_size && score < best_score) {
>+	/* Check the cost, update best */
>+	if (avail >= real_size && cost < best_cost) {
> 	    best = begin;
>-	    best_score = score;
>+	    best_cost = cost;
> 	}
> 
> 	avail -= begin->size;
>-	score -= AREA_SCORE(begin);
>+	cost -= begin->eviction_cost;
> 	begin = begin->next;
>     }
> 
>@@ -244,6 +260,7 @@ exaOffscreenAlloc (ScreenPtr pScreen, int size, int align,
> 	new_area->state = ExaOffscreenAvail;
> 	new_area->save = NULL;
> 	new_area->last_use = 0;
>+	new_area->eviction_cost = 0;
> 	new_area->next = area->next;
> 	area->next = new_area;
> 	area->size = real_size;
>@@ -409,6 +426,7 @@ exaOffscreenFree (ScreenPtr pScreen, ExaOffscreenArea *area)
>     area->state = ExaOffscreenAvail;
>     area->save = NULL;
>     area->last_use = 0;
>+    area->eviction_cost = 0;
>     /*
>      * Find previous area
>      */
>@@ -474,6 +492,7 @@ exaOffscreenInit (ScreenPtr pScreen)
>     area->save = NULL;
>     area->next = NULL;
>     area->last_use = 0;
>+    area->eviction_cost = 0;
> 
>     /* Add it to the free areas */
>     pExaScr->info->offScreenAreas = area;

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Attachments on bug 15513: 15919 | 15920 | 15929 | 15949 | 15950 | 16051 | 16053

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