This avoids locking Cc for too long by trying to read-ahead data which
is already in cache.
We now will only schedule a read ahead if next read should bring us
to a new VACB (perhaps not in cache).
This notably fixes Inkscape setup which was slown down by read-ahead
due to continous 1 byte reads.
Thanks to Thomas for his help on this issue.
CORE-14395
/* If that was a successful sync read operation, let's handle read ahead */
if (Operation == CcOperationRead && Length == 0 && Wait)
{
- /* If file isn't random access, schedule next read */
- if (!BooleanFlagOn(FileObject->Flags, FO_RANDOM_ACCESS))
+ /* If file isn't random access and next read may get us cross VACB boundary,
+ * schedule next read
+ */
+ if (!BooleanFlagOn(FileObject->Flags, FO_RANDOM_ACCESS) &&
+ (CurrentOffset - 1) / VACB_MAPPING_GRANULARITY != (CurrentOffset + BytesCopied - 1) / VACB_MAPPING_GRANULARITY)
{
CcScheduleReadAhead(FileObject, (PLARGE_INTEGER)&FileOffset, BytesCopied);
}