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* Since cache_io() can now work with NULL buffers, I resurrected prefetching

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using it.
* IOW cache_prefetch_vnode() should work again now.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26468 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2008-07-17 01:10:18 +00:00
parent 51c99056b5
commit 13ea2be597
1 changed files with 3 additions and 54 deletions
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57
src/system/kernel/cache/file_cache.cpp vendored
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@ -760,13 +760,12 @@ file_cache_control(const char *subsystem, uint32 function, void *buffer,
extern "C" void
cache_prefetch_vnode(struct vnode *vnode, off_t offset, size_t size)
{
#if 0
vm_cache *cache;
if (vfs_get_vnode_cache(vnode, &cache, false) != B_OK)
return;
file_cache_ref *ref = (struct file_cache_ref *)
((vnode_store *)cache->store)->file_cache_ref;
file_cache_ref *ref
= (file_cache_ref *)((vnode_store *)cache->store)->file_cache_ref;
off_t fileSize = cache->virtual_size;
if (size > fileSize)
@ -776,58 +775,8 @@ cache_prefetch_vnode(struct vnode *vnode, off_t offset, size_t size)
if (size > 4 * 1024 * 1024)
size = 4 * 1024 * 1024;
size_t bytesLeft = size, lastLeft = size;
off_t lastOffset = offset;
size_t lastSize = 0;
mutex_lock(&cache->lock);
for (; bytesLeft > 0; offset += B_PAGE_SIZE) {
// check if this page is already in memory
addr_t virtualAddress;
restart:
vm_page *page = vm_cache_lookup_page(cache, offset);
if (page != NULL) {
if (page->state == PAGE_STATE_BUSY) {
// if busy retry again later
ConditionVariableEntry entry;
entry.Add(page);
mutex_unlock(&cache->lock);
entry.Wait();
mutex_lock(&cache->lock);
goto restart;
}
// it is, so let's satisfy in the first part of the request
if (lastOffset < offset) {
size_t requestSize = offset - lastOffset;
read_into_cache(ref, lastOffset, requestSize, NULL, 0);
}
if (bytesLeft <= B_PAGE_SIZE) {
// we've read the last page, so we're done!
goto out;
}
// prepare a potential gap request
lastOffset = offset + B_PAGE_SIZE;
lastLeft = bytesLeft - B_PAGE_SIZE;
}
if (bytesLeft <= B_PAGE_SIZE)
break;
bytesLeft -= B_PAGE_SIZE;
}
// read in the last part
read_into_cache(ref, lastOffset, lastLeft, NULL, 0);
out:
mutex_unlock(&cache->lock);
cache_io(ref, NULL, offset, 0, &size, false);
vm_cache_release_ref(cache);
#endif
}