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path: root/fs/ocfs2/reservations.h
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2010-05-05ocfs2: make ocfs2_adjust_resv_from_alloc simple.Tao Ma
When we allocate some bits from the reservation, we always allocate from the r_start(see ocfs2_resmap_resv_bits). So there should be no reason to check between r_start and start. And I don't think we will change this behaviour later by allocating from some bits after r_start. Why not make ocfs2_adjust_resv_from_alloc simple for now? The only chance we have to adjust the reservation is when we haven't reached the end. With this patch, the function is more readable. Note: btw, this patch also fixes an original bug in the function which I haven't found before. if (end < ocfs2_resv_end(resv)) rhs = end - ocfs2_resv_end(resv); This code is of course buggy. ;) Signed-off-by: Tao Ma <tao.ma@oracle.com> Acked-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2010-05-05ocfs2: Add dir_resv_level mount optionMark Fasheh
The default behavior for directory reservations stays the same, but we add a mount option so people can tweak the size of directory reservations according to their workloads. Signed-off-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2010-05-05ocfs2: change default reservation window sizesMark Fasheh
The default reservation size of 4 (32-bit windows) is a bit too ambitious. Scale it back to 16 bits (resv_level=2). I have been testing various sizes on a 4-node cluster which runs a mixed workload that is heavily threaded. With a 256MB local alloc, I get *roughly* the following levels of average file fragmentation: resv_level=0 70% resv_level=1 21% resv_level=2 23% resv_level=3 24% resv_level=4 60% resv_level=5 did not test resv_level=6 60% resv_level=2 seemed like a good compromise between not letting windows be too small, but not so big that heavier workloads will immediately suffer without tuning. This patch also change the behavior of directory reservations - they now track file reservations. The previous compromise of giving directory windows only 8 bits wound up fragmenting more at some window sizes because file allocations had smaller unused windows to poach from. Signed-off-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2010-05-05ocfs2: use allocation reservations for directory dataMark Fasheh
Use the reservations system for unindexed dir tree allocations. We don't bother with the indexed tree as reads from it are mostly random anyway. Directory reservations are marked seperately, to allow the reservations code a chance to optimize their window sizes. This patch allocates only 8 bits for directory windows as they generally are not expected to grow as quickly as file data. Future improvements to dir window sizing can trivially be made. Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2010-05-05ocfs2: allocation reservationsMark Fasheh
This patch improves Ocfs2 allocation policy by allowing an inode to reserve a portion of the local alloc bitmap for itself. The reserved portion (allocation window) is advisory in that other allocation windows might steal it if the local alloc bitmap becomes full. Otherwise, the reservations are honored and guaranteed to be free. When the local alloc window is moved to a different portion of the bitmap, existing reservations are discarded. Reservation windows are represented internally by a red-black tree. Within that tree, each node represents the reservation window of one inode. An LRU of active reservations is also maintained. When new data is written, we allocate it from the inodes window. When all bits in a window are exhausted, we allocate a new one as close to the previous one as possible. Should we not find free space, an existing reservation is pulled off the LRU and cannibalized. Signed-off-by: Mark Fasheh <mfasheh@suse.com>