Messages in this thread | | | Subject | Re: [PATCH] block: respect virtual boundary mask in bvecs | From | Bart Van Assche <> | Date | Wed, 07 Nov 2018 08:10:19 -0800 |
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On Tue, 2018-11-06 at 19:30 -0800, Sagi Grimberg wrote: > > > How about changing that expression into the following to make it easier > > > for the compiler to optimize this code? > > > > > > (offset | (bprv->bv_offset + bprv->bv_len)) & queue_virt_boundary(q) > > > > Uhm I have to admit I'm not really able to parse the above expression. > > Sure GCC will do it but I think it's less readable (at least for me). > > Let's see what other's think. > > I personally not a huge fan of decoding complicated expressions. But if > others are fine with it then I am too...
What I proposed is not a new pattern. It is a pattern that is already used elsewhere in the Linux kernel. A few examples:
From dmabounce.c:
/* Figure out if we need to bounce from the DMA mask. */ if ((dma_addr | (dma_addr + size - 1)) & ~mask) return 1;
From dma-direct.h:
if ((addr | (addr + size - 1)) & ~mask) return 0;
Bart.
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