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dix: Bump MAXHASHSIZE for the resource db [v2] 

[This was originally a workaround for a client-side resource leak:

http://lists.freedesktop.org/archives/xorg-devel/2012-November/034555.html

Obviously that's a broken app, but the performance problem it
illustrates - that walking the linked list ends up burning all your CPU
time - is real enough. - ajax]

v2: Replace with a shorter code sequence which computes the same
    results for all but numBits == 7

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Keith Packard 2016-10-28 09:28:32 -07:00
parent 356db2340f
commit c85f81825e
1 changed files with 9 additions and 24 deletions
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33
dix/resource.c
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@ -156,7 +156,7 @@ static void RebuildTable(int /*client */
#define INITBUCKETS 64 #define INITBUCKETS 64
#define INITHASHSIZE 6 #define INITHASHSIZE 6
#define MAXHASHSIZE 11 #define MAXHASHSIZE 16
typedef struct _Resource { typedef struct _Resource {
struct _Resource *next; struct _Resource *next;
@ -668,29 +668,14 @@ InitClientResources(ClientPtr client)
int int
HashResourceID(XID id, int numBits) HashResourceID(XID id, int numBits)
{ {
id &= RESOURCE_ID_MASK; static XID mask;
switch (numBits)
{ if (!mask)
case 6: mask = RESOURCE_ID_MASK;
return ((int)(0x03F & (id ^ (id>>6) ^ (id>>12)))); id &= mask;
case 7: if (numBits < 9)
return ((int)(0x07F & (id ^ (id>>7) ^ (id>>13)))); return (id ^ (id >> numBits) ^ (id >> (numBits<<1))) & ~((~0) << numBits);
case 8: return (id ^ (id >> numBits)) & ~((~0) << numBits);
return ((int)(0x0FF & (id ^ (id>>8) ^ (id>>16))));
case 9:
return ((int)(0x1FF & (id ^ (id>>9))));
case 10:
return ((int)(0x3FF & (id ^ (id>>10))));
case 11:
return ((int)(0x7FF & (id ^ (id>>11))));
}
if (numBits >= 11)
return ((int)(0x7FF & (id ^ (id>>11))));
else
{
assert(numBits >= 0);
return id & ~((~0) << numBits);
}
} }
static XID static XID