Hi, Any update over my previous reply? Thanks, Sreekanth On Thu, Feb 27, 2020 at 6:11 PM Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx> wrote: > > On Wed, Feb 26, 2020 at 12:12 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > > > On Tue, Feb 11, 2020 at 05:18:12AM -0500, suganath-prabu.subramani@xxxxxxxxxxxx wrote: > > > From: Suganath Prabu S <suganath-prabu.subramani@xxxxxxxxxxxx> > > > > > > For INVADER_SERIES each set of 8 reply queues (0 - 7, 8 - 15,..)and > > > VENTURA_SERIES each set of 16 reply queues (0 - 15, 16 - 31,..)should > > > be within 4 GB boundary.Driver uses limitation of VENTURA_SERIES > > > to manage INVADER_SERIES as well. So here driver is allocating the DMA > > > able memory for RDPQ's accordingly. > > > > > > For RDPQ buffers, driver creates two separate pci pool. > > > "reply_post_free_dma_pool" and "reply_post_free_dma_pool_align" > > > First driver tries allocating memory from the pool > > > "reply_post_free_dma_pool", if the requested allocation are > > > within same 4gb region then proceeds for next allocations. > > > If not, allocates from reply_post_free_dma_pool_align which is > > > size aligned and if success, it will always meet same 4gb region > > > requirement > > > > I don't fully understand the changelog here, and how having two > > dma pools including one aligned is all that good. > > The requirement is that driver needs a set of memory blocks of size > ~106 KB and this block should not cross the 4gb boundary (i.e. > starting & end address of this block should have the same higher 32 > bit address). So what we are doing is that first we allocate a block > from generic pool 'reply_post_free_dma_pool' and we check whether this > block cross the 4gb boundary or not, if it is yes then we free this > block and we try to allocate block once gain from pool > 'reply_post_free_dma_pool_align' where we alignment of this pool is > set to power of two from block size. Hoping that second time > allocation block will not cross the 4 gb boundary. > > Is there any interface or API which make sures that it always > allocates the required size memory block and also satisfies 4bg > boundary condtion? > > > > > Why not do a single dma_alloc_coherent and then subdvide it given > > that all the allocations from the DMA pool seem to happen at HBA > > initialization time anyway, invalidating the need for the dynamic > > nature of the dma pools. > > we need 8 blocks of block size ~106 KB, so total will be ~848 KB and > most of the times we may not get this much size continuous single > block memory and also this block should satisfy the 4gb boundary > requirement. And hence driver is allocating each block individually. > > Regards, > Sreekanth
