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* Sequential write accesses were never detected, due to an incorrect check.

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* The previous code would have scheduled a single page to be written out (if it
  would have ever been triggered), now we schedule the complete previous write
  access. This greatly speeds up a "dd if=/dev/zero of=test ..." beyond the
  size of available memory.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30276 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2009-04-20 08:02:51 +00:00
parent 5e172bc680
commit 8a26f35a6d
1 changed files with 26 additions and 15 deletions
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41
src/system/kernel/cache/file_cache.cpp vendored
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@ -51,7 +51,22 @@ struct file_cache_ref {
// write vs. read)
int32 last_access_index;
uint16 disabled_count;
bool last_access_was_write;
inline void SetLastAccess(int32 index, off_t access, bool isWrite)
{
// we remember writes as negative offsets
last_access[index] = isWrite ? -access : access;
}
inline off_t LastAccess(int32 index, bool isWrite)
{
return isWrite ? -last_access[index] : last_access[index];
}
inline uint32 LastAccessPageOffset(int32 index, bool isWrite)
{
return LastAccess(index, isWrite) >> PAGE_SHIFT;
}
};
typedef status_t (*cache_func)(file_cache_ref *ref, void *cookie, off_t offset,
@ -104,14 +119,10 @@ push_access(file_cache_ref *ref, off_t offset, size_t bytes, bool isWrite)
if (previous < 0)
previous = LAST_ACCESSES - 1;
if (offset != ref->last_access[previous])
if (offset != ref->LastAccess(previous, isWrite))
ref->last_access[previous] = 0;
// we remember writes as negative offsets
if (isWrite)
ref->last_access[index] = -offset - bytes;
else
ref->last_access[index] = offset + bytes;
ref->SetLastAccess(index, offset + bytes, isWrite);
if (++index >= LAST_ACCESSES)
index = 0;
@ -132,14 +143,14 @@ reserve_pages(file_cache_ref *ref, size_t reservePages, bool isWrite)
if (isWrite) {
// just schedule some pages to be written back
for (VMCachePagesTree::Iterator it = cache->pages.GetIterator();
vm_page* page = it.Next();) {
if (page->state == PAGE_STATE_MODIFIED) {
// TODO: for now, we only schedule one
vm_page_schedule_write_page(page);
break;
}
}
int32 index = ref->last_access_index;
int32 previous = index - 1;
if (previous < 0)
previous = LAST_ACCESSES - 1;
vm_page_schedule_write_page_range(cache,
ref->LastAccessPageOffset(previous, true),
ref->LastAccessPageOffset(index, true));
} else {
// free some pages from our cache
// TODO: start with oldest