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Added optional debug facility (can be enabled by defining

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TRACK_PAGE_USAGE_STATS): The page daemon tracks the distribution of page
usage counts. Can be printed using the "page_usage" command.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@27182 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold
2008-08-23 23:41:44 +00:00
parent aacb158ca2
commit ded820241d
1 changed files with 95 additions and 1 deletions
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src/system/kernel/vm/vm_daemons.cpp
+95 -1
View File
@@ -8,6 +8,8 @@
#include <signal.h>
#include <algorithm>
#include <OS.h>
#include <vm.h>
@@ -17,6 +19,9 @@
#include "VMAnonymousCache.h"
//#define TRACK_PAGE_USAGE_STATS 1
const static uint32 kMinScanPagesCount = 512;
const static uint32 kMaxScanPagesCount = 8192;
const static bigtime_t kMinScanWaitInterval = 50000LL; // 50 ms
@@ -26,6 +31,14 @@ static uint32 sLowPagesCount;
static sem_id sPageDaemonSem;
static uint32 sNumPages;
#ifdef TRACK_PAGE_USAGE_STATS
static page_num_t sPageUsageArrays[512];
static page_num_t* sPageUsage = sPageUsageArrays;
static page_num_t sPageUsagePageCount;
static page_num_t* sNextPageUsage = sPageUsageArrays + 256;
static page_num_t sNextPageUsagePageCount;
#endif
PageCacheLocker::PageCacheLocker(vm_page* page, bool dontWait)
:
@@ -90,6 +103,67 @@ PageCacheLocker::Unlock()
// #pragma mark -
#ifdef TRACK_PAGE_USAGE_STATS
static void
track_page_usage(vm_page* page)
{
if (page->wired_count == 0) {
sNextPageUsage[(int32)page->usage_count + 128]++;
sNextPageUsagePageCount++;
}
}
static void
update_page_usage_stats()
{
std::swap(sPageUsage, sNextPageUsage);
sPageUsagePageCount = sNextPageUsagePageCount;
memset(sNextPageUsage, 0, sizeof(page_num_t) * 256);
sNextPageUsagePageCount = 0;
// compute average
if (sPageUsagePageCount > 0) {
int64 sum = 0;
for (int32 i = 0; i < 256; i++)
sum += (int64)sPageUsage[i] * (i - 128);
dprintf("average page usage: %f (%lu pages)\n",
(float)sum / sPageUsagePageCount, sPageUsagePageCount);
}
}
static int
dump_page_usage_stats(int argc, char** argv)
{
kprintf("distribution of page usage counts (%lu pages):",
sPageUsagePageCount);
int64 sum = 0;
for (int32 i = 0; i < 256; i++) {
if (i % 8 == 0)
kprintf("\n%4ld:", i - 128);
int64 count = sPageUsage[i];
sum += count * (i - 128);
kprintf(" %9llu", count);
}
kprintf("\n\n");
kprintf("average usage count: %f\n",
sPageUsagePageCount > 0 ? (float)sum / sPageUsagePageCount : 0);
return 0;
}
#endif
static void
clear_page_activation(int32 index)
{
@@ -128,12 +202,20 @@ check_page_activation(int32 index)
} else if (page->usage_count < 127)
page->usage_count++;
#ifdef TRACK_PAGE_USAGE_STATS
track_page_usage(page);
#endif
return false;
}
if (page->usage_count > -128)
page->usage_count--;
#ifdef TRACK_PAGE_USAGE_STATS
track_page_usage(page);
#endif
if (page->usage_count < 0) {
uint32 flags;
vm_remove_all_page_mappings(page, &flags);
@@ -216,8 +298,12 @@ dprintf("wait interval %Ld, scan pages %lu, free %lu, target %lu\n",
for (uint32 i = 0; i < scanPagesCount && leftToFree > 0; i++) {
if (clearPage == 0)
dprintf("clear through\n");
if (checkPage == 0)
if (checkPage == 0) {
dprintf("check through\n");
#ifdef TRACK_PAGE_USAGE_STATS
update_page_usage_stats();
#endif
}
clear_page_activation(clearPage);
if (check_page_activation(checkPage))
@@ -261,6 +347,14 @@ vm_schedule_page_scanner(uint32 target)
status_t
vm_daemon_init()
{
#ifdef TRACK_PAGE_USAGE_STATS
add_debugger_command_etc("page_usage", &dump_page_usage_stats,
"Dumps statistics about page usage counts",
"\n"
"Dumps statistics about page usage counts.\n",
B_KDEBUG_DONT_PARSE_ARGUMENTS);
#endif
sPageDaemonSem = create_sem(0, "page daemon");
sNumPages = vm_page_num_pages();