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Halve the memory being internally allocated by the blist allocator. In

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short, half of the memory that is allocated to implement the radix tree is
wasted because we did not change "u_daddr_t" to be a 64-bit unsigned int
when we changed "daddr_t" to be a 64-bit (signed) int.  (See r96849 and
r96851.)

Reviewed by:	kib, markj
Tested by:	pho
MFC after:	5 days
Differential Revision:	https://reviews.freebsd.org/D11028
This commit is contained in:
Alan Cox 2017-06-05 17:14:16 +00:00
parent dc09cfbf08
commit 064650c180
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=319604
3 changed files with 6 additions and 7 deletions
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4
sys/kern/subr_blist.c
View File

@ -366,7 +366,7 @@ blst_leaf_alloc(
j >>= 1;
mask >>= j;
}
scan->u.bmu_bitmap &= ~(1 << r);
scan->u.bmu_bitmap &= ~((u_daddr_t)1 << r);
return(blk + r);
}
if (count <= BLIST_BMAP_RADIX) {
@ -658,7 +658,7 @@ static void blst_copy(
int i;
for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
if (v & (1 << i))
if (v & ((u_daddr_t)1 << i))
blist_free(dest, blk + i, 1);
}
}

4
sys/sys/blist.h
View File

@ -44,7 +44,7 @@
* ops.
*
* SWAPBLK_NONE is returned on failure. This module is typically
* capable of managing up to (2^31) blocks per blist, though
* capable of managing up to (2^63) blocks per blist, though
* the memory utilization would be insane if you actually did
* that. Managing something like 512MB worth of 4K blocks
* eats around 32 KBytes of memory.
@ -56,7 +56,7 @@
#ifndef _SYS_BLIST_H_
#define _SYS_BLIST_H_
typedef u_int32_t u_daddr_t; /* unsigned disk address */
typedef uint64_t u_daddr_t; /* unsigned disk address */
/*
* note: currently use SWAPBLK_NONE as an absolute value rather then

5
sys/vm/swap_pager.c
View File

@ -116,9 +116,8 @@ __FBSDID("$FreeBSD$");
#include <geom/geom.h>
/*
* SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16
* or 32 pages per allocation.
* The 32-page limit is due to the radix code (kern/subr_blist.c).
* MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64.
* The 64-page limit is due to the radix code (kern/subr_blist.c).
*/
#ifndef MAX_PAGEOUT_CLUSTER
#define MAX_PAGEOUT_CLUSTER 16