From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuri Tikhonov Subject: Re[4]: [PATCH 03/11][v3] async_tx: add support for asynchronous RAID6 recovery operations Date: Sat, 17 Jan 2009 15:26:57 +0300 Message-ID: <20244211.20090117152657@emcraft.com> References: <200901130343.14016.yur@emcraft.com> <498243073.20090116145142@emcraft.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Dan Williams Cc: linux-raid@vger.kernel.org, linuxppc-dev@ozlabs.org, dzu@denx.de, wd@denx.de, yanok@emcraft.com List-Id: linux-raid.ids On Friday, January 16, 2009 you wrote: > On Fri, Jan 16, 2009 at 4:51 AM, Yuri Tikhonov wrote: >> The reason why I preferred to use async_pq() instead of async_xor() >> here is to maximize the chance that the whole D+D recovery operation >> will be handled in one ADMA device, i.e. without channels switch and >> the latency introduced because of that. >> > This should be a function of the async_tx_find_channel implementation. > The default version tries to keep a chain of operations on one > channel. > struct dma_chan * > __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx, > enum dma_transaction_type tx_type) > { > /* see if we can keep the chain on one channel */ > if (depend_tx && > dma_has_cap(tx_type, depend_tx->chan->device->cap_mask)) > return depend_tx->chan; > return dma_find_channel(tx_type); > } Right. Then I need to update my ADMA driver, and add support for explicit DMA_XOR capability on channels which can process DMA_PQ. Thanks. Regards, Yuri -- Yuri Tikhonov, Senior Software Engineer Emcraft Systems, www.emcraft.com