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The file cache now completely bypasses the cache for writes equal or larger

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than 64KB. Reads should probably get a similar logic, at least if memory is
tight.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22857 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2007-11-08 09:30:58 +00:00
parent 67f0ddf604
commit 09149281e0
1 changed files with 48 additions and 27 deletions
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75
src/system/kernel/cache/file_cache.cpp vendored
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@ -78,6 +78,10 @@ struct file_cache_ref {
bool last_access_was_write;
};
typedef status_t (*cache_func)(file_cache_ref *ref, off_t offset,
size_t numBytes, int32 pageOffset, addr_t buffer, size_t bufferSize,
size_t lastReservedPages, size_t reservePages);
static struct cache_module_info *sCacheModule;
@ -853,10 +857,32 @@ write_to_cache(file_cache_ref *ref, off_t offset, size_t numBytes,
static status_t
satisfy_cache_io(file_cache_ref *ref, off_t offset, addr_t buffer,
int32 &pageOffset, size_t bytesLeft, size_t &reservePages,
write_to_file(file_cache_ref *ref, off_t offset, size_t numBytes,
int32 pageOffset, addr_t buffer, size_t bufferSize,
size_t lastReservedPages, size_t reservePages)
{
iovec vec;
vec.iov_base = (void *)buffer;
vec.iov_len = bufferSize;
mutex_unlock(&ref->cache->lock);
vm_page_unreserve_pages(lastReservedPages);
status_t status = pages_io(ref, offset, &vec, 1, &numBytes, true);
if (status == B_OK)
reserve_pages(ref, reservePages, true);
mutex_lock(&ref->cache->lock);
return status;
}
static inline status_t
satisfy_cache_io(file_cache_ref *ref, cache_func function, off_t offset,
addr_t buffer, int32 &pageOffset, size_t bytesLeft, size_t &reservePages,
off_t &lastOffset, addr_t &lastBuffer, int32 &lastPageOffset,
size_t &lastLeft, size_t &lastReservedPages, bool doWrite)
size_t &lastLeft, size_t &lastReservedPages)
{
if (lastBuffer == buffer)
return B_OK;
@ -865,14 +891,8 @@ satisfy_cache_io(file_cache_ref *ref, off_t offset, addr_t buffer,
reservePages = min_c(MAX_IO_VECS,
(lastLeft - requestSize + B_PAGE_SIZE - 1) >> PAGE_SHIFT);
status_t status;
if (doWrite) {
status = write_to_cache(ref, lastOffset, requestSize, lastPageOffset,
lastBuffer, requestSize, lastReservedPages, reservePages);
} else {
status = read_into_cache(ref, lastOffset, requestSize, lastPageOffset,
lastBuffer, requestSize, lastReservedPages, reservePages);
}
status_t status = function(ref, lastOffset, requestSize, lastPageOffset,
lastBuffer, requestSize, lastReservedPages, reservePages);
if (status == B_OK) {
lastReservedPages = reservePages;
lastBuffer = buffer;
@ -917,6 +937,15 @@ cache_io(void *_cacheRef, off_t offset, addr_t buffer, size_t *_size,
if (size == 0)
return B_OK;
cache_func function;
if (doWrite) {
if (size >= 65536)
function = write_to_file;
else
function = write_to_cache;
} else
function = read_into_cache;
// "offset" and "lastOffset" are always aligned to B_PAGE_SIZE,
// the "last*" variables always point to the end of the last
// satisfied request part
@ -941,9 +970,9 @@ cache_io(void *_cacheRef, off_t offset, addr_t buffer, size_t *_size,
// in the near future, we need to satisfy the request of the pages
// we didn't get yet (to make sure no one else interferes in the
// mean time).
status_t status = satisfy_cache_io(ref, offset, buffer, pageOffset,
bytesLeft, reservePages, lastOffset, lastBuffer, lastPageOffset,
lastLeft, lastReservedPages, doWrite);
status_t status = satisfy_cache_io(ref, function, offset, buffer,
pageOffset, bytesLeft, reservePages, lastOffset, lastBuffer,
lastPageOffset, lastLeft, lastReservedPages);
if (status != B_OK)
return status;
@ -1009,9 +1038,9 @@ cache_io(void *_cacheRef, off_t offset, addr_t buffer, size_t *_size,
offset += B_PAGE_SIZE;
if (buffer - lastBuffer + lastPageOffset >= kMaxChunkSize) {
status_t status = satisfy_cache_io(ref, offset, buffer, pageOffset,
bytesLeft, reservePages, lastOffset, lastBuffer, lastPageOffset,
lastLeft, lastReservedPages, doWrite);
status_t status = satisfy_cache_io(ref, function, offset, buffer,
pageOffset, bytesLeft, reservePages, lastOffset, lastBuffer,
lastPageOffset, lastLeft, lastReservedPages);
if (status != B_OK)
return status;
}
@ -1019,16 +1048,8 @@ cache_io(void *_cacheRef, off_t offset, addr_t buffer, size_t *_size,
// fill the last remaining bytes of the request (either write or read)
status_t status;
if (doWrite) {
status = write_to_cache(ref, lastOffset, lastLeft, lastPageOffset,
lastBuffer, lastLeft, lastReservedPages, 0);
} else {
status = read_into_cache(ref, lastOffset, lastLeft, lastPageOffset,
lastBuffer, lastLeft, lastReservedPages, 0);
}
return status;
return function(ref, lastOffset, lastLeft, lastPageOffset,
lastBuffer, lastLeft, lastReservedPages, 0);
}