From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755408Ab1KQCXa (ORCPT ); Wed, 16 Nov 2011 21:23:30 -0500 Received: from mailout3.samsung.com ([203.254.224.33]:52367 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754855Ab1KQCX3 (ORCPT ); Wed, 16 Nov 2011 21:23:29 -0500 X-AuditID: cbfee61a-b7cf1ae00000208e-6e-4ec47014e798 From: Seungwon Jeon To: merez@codeaurora.org Cc: svenkatr@ti.com, linux-mmc@vger.kernel.org, "'Chris Ball'" , linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, kgene.kim@samsung.com, dh.han@samsung.com References: In-reply-to: Subject: RE: [PATCH] mmc: core: Add packed command for eMMC4.5 device Date: Thu, 17 Nov 2011 11:23:16 +0900 Message-id: <004b01cca4cf$dd318f60$9794ae20$%jun@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=Windows-1252 Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: AcykVjbGu+qe8BHQS4mobrmixvfr7gAeXfOg Content-language: ko X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Maya Erez wrote: > > > + if (reqs >= 2) { > > + mmc_blk_packed_hdr_wrq_prep(mq->mqrq_cur, card, mq, reqs); > > + if (rq_data_dir(rqc) == READ) { > > + areq = &mq->mqrq_cur->mmc_active; > > + mmc_wait_for_req(card->host, areq->mrq); > Packing read requests requires preparation of two requests. After sending > the header we wait for its completion before sending the next request > (mmc_wait_for_req is used). Therefore, if we try to pack 2 read requests > we might end up with worse performance in comparison to sending each > request by itself (which allows the preparation of one request while the > other is sent). > I suggest to check the size of the packed commands list and in case it is > less than 3 send the requests one by one. If you move mmc_blk_chk_packable > to queue.c after the first fetch this change should be very easy and can > be done by removing the requests from the packed_list and calling issue_fn > for each one of them. Sending header for packed read which doesn't require nand program unlike normal data, so it may not spend long time. Which point you think is the overhead of packed two-requests in comparison to individual request? > > Thanks, > Maya Erez > Consultant for Qualcomm Innovation Center, Inc. > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html