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| author | Andrea Arcangeli <andrea@qumranet.com> | 2008-04-02 09:06:44 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-04-02 09:06:44 +0200 |
| commit | 00d61e3e8c12d5f395b167856d2b3c430816afb0 (patch) | |
| tree | 757df09b076810b40ee3431a394882a2be860a68 /block | |
| parent | 0e81a8ae37687845f7cdfa2adce14ea6a5f1dd34 (diff) | |
| download | lwn-00d61e3e8c12d5f395b167856d2b3c430816afb0.tar.gz lwn-00d61e3e8c12d5f395b167856d2b3c430816afb0.zip | |
Fix bounce setting for 64-bit
Looking a bit closer into this regression the reason this can't be
right is that dma_addr common default is BLK_BOUNCE_HIGH and most
machines have less than 4G. So if you do:
if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
dma = 1
that will translate to:
if (BLK_BOUNCE_HIGH <= BLK_BOUNCE_HIGH)
dma = 1
So for 99% of hardware this will trigger unnecessary GFP_DMA
allocations and isa pooling operations.
Also note how the 32bit code still does b_pfn < blk_max_low_pfn.
I guess this is what you were looking after. I didn't verify but as
far as I can tell, this will stop the regression with isa dma
operations at boot for 99% of blkdev/memory combinations out there and
I guess this fixes the setups with >4G of ram and 32bit pci cards as
well (this also retains symmetry with the 32bit code).
Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-settings.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 1344a0ea5cc6..5713f7e5cbd2 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -140,7 +140,7 @@ void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) /* Assume anything <= 4GB can be handled by IOMMU. Actually some IOMMUs can handle everything, but I don't know of a way to test this here. */ - if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) + if (b_pfn < (min_t(u64, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) dma = 1; q->bounce_pfn = max_low_pfn; #else |