On Tue, Apr 01 2008, Andrea Arcangeli wrote: > 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 <[EMAIL PROTECTED]>
Thanks Andrea, this looks much saner! -- Jens Axboe ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
