On Wed, 2015-09-23 at 00:28 -0500, Zhao Qiang-B45475 wrote: > On Wen, Sep 23, 2015 at 12:03 AM +0800, Wood Scott-B07421 wrote: > > > -----Original Message----- > > From: Wood Scott-B07421 > > Sent: Wednesday, September 23, 2015 12:03 PM > > To: Zhao Qiang-B45475 > > Cc: linux-kernel@vger.kernel.org; linuxppc-...@lists.ozlabs.org; > > lau...@codeaurora.org; Xie Xiaobo-R63061; b...@kernel.crashing.org; Li > > Yang-Leo-R58472; pau...@samba.org > > Subject: Re: [PATCH v10 3/5] CPM/QE: use genalloc to manage CPM/QE muram > > > > On Tue, 2015-09-22 at 21:20 -0500, Zhao Qiang-B45475 wrote: > > > On Wen, Sep 23, 2015 at 8:19 AM +0800, Wood Scott-B07421 wrote: > > > > > > > > > > { > > > > > > > - int ret; > > > > > > > + > > > > > > > + unsigned long start; > > > > > > > unsigned long flags; > > > > > > > + unsigned long size_alloc = size; struct muram_block *entry; > > > > > > > + int end_bit; int order = muram_pool->min_alloc_order; > > > > > > > > > > > > > > spin_lock_irqsave(&cpm_muram_lock, flags); > > > > > > > - ret = rh_free(&cpm_muram_info, offset); > > > > > > > + end_bit = (offset >> order) + ((size + (1UL << order) - 1) > > > > > > > + >> > > > > > > order); > > > > > > > + if ((offset + size) > (end_bit << order)) > > > > > > > + size_alloc = size + (1UL << order); > > > > > > > > > > > > Why do you need to do all these calculations here? > > > > > > > > > > So do it in gen_pool_fixed_alloc? > > > > > > > > Could you explain why they're needed at all? > > > > > > Why it does the calculations? > > > If the min block of gen_pool is 8 bytes, and I want to allocate a > > > Region with offset=7, size=8bytes, I actually need block 0 and block > > > 1, And the allocation will give me block 0. > > > > How can you have offset 7 if the minimum order is 2 bytes? > > Offset has no relationship with minimum order, it is not decided by minimum > order.
All allocations begin and end on a multiple of the minimum order. > I want to allocate a specific region with offset=7, then algo to calculate > the block bit. > And I just take it for example, it is not I really need to region offset=7. Do you really need any fixed allocations that begin on an odd address? > So, now minimum order is 2 bytes. If offset=7, size=4bytes needed, it > actually allocate 6-12 to me. Why 6-12 and not 6-10? -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/