From patchwork Thu Apr 16 13:49:26 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Don Brace X-Patchwork-Id: 6226301 Return-Path: X-Original-To: patchwork-linux-scsi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 8A7479F1C4 for ; Thu, 16 Apr 2015 13:50:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A5605202AE for ; Thu, 16 Apr 2015 13:50:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B300E2024D for ; Thu, 16 Apr 2015 13:50:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965094AbbDPNuc (ORCPT ); Thu, 16 Apr 2015 09:50:32 -0400 Received: from g9t5009.houston.hp.com ([15.240.92.67]:51387 "EHLO g9t5009.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965088AbbDPNu0 (ORCPT ); Thu, 16 Apr 2015 09:50:26 -0400 Received: from g9t2301.houston.hp.com (g9t2301.houston.hp.com [16.216.185.78]) by g9t5009.houston.hp.com (Postfix) with ESMTP id 7AF734C1; Thu, 16 Apr 2015 13:50:26 +0000 (UTC) Received: from [127.0.1.1] (brunhilda.americas.hpqcorp.net [16.100.201.25]) by g9t2301.houston.hp.com (Postfix) with ESMTP id 5F42967; Thu, 16 Apr 2015 13:50:26 +0000 (UTC) Subject: [PATCH v4 30/43] hpsa: performance tweak for hpsa_scatter_gather() From: Don Brace To: scott.teel@pmcs.com, Kevin.Barnett@pmcs.com, james.bottomley@parallels.com, hch@infradead.org, Justin.Lindley@pmcs.com, brace@pmcs.com Cc: linux-scsi@vger.kernel.org Date: Thu, 16 Apr 2015 08:49:26 -0500 Message-ID: <20150416134926.30238.26368.stgit@brunhilda> In-Reply-To: <20150416134224.30238.66082.stgit@brunhilda> References: <20150416134224.30238.66082.stgit@brunhilda> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Webb Scales Divide the loop in hpsa_scatter_gather() into two, one for the initial SG list and a second one for the chained list, if any. This allows the conditional check which resets the indicies for the chained list to be performed outside the loop instead of being done on every iteration inside the loop. Reviewed-by: Scott Teel Reviewed-by: Kevin Barnett Signed-off-by: Webb Scales Signed-off-by: Don Brace Reviewed-by: Hannes Reinecke Reviewed-by: Tomas Henzl --- drivers/scsi/hpsa.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c index 753026a..5e12520 100644 --- a/drivers/scsi/hpsa.c +++ b/drivers/scsi/hpsa.c @@ -3679,7 +3679,7 @@ static int hpsa_scatter_gather(struct ctlr_info *h, struct scsi_cmnd *cmd) { struct scatterlist *sg; - int use_sg, i, sg_index, chained; + int use_sg, i, sg_limit, chained, last_sg; struct SGDescriptor *curr_sg; BUG_ON(scsi_sg_count(cmd) > h->maxsgentries); @@ -3691,22 +3691,39 @@ static int hpsa_scatter_gather(struct ctlr_info *h, if (!use_sg) goto sglist_finished; + /* + * If the number of entries is greater than the max for a single list, + * then we have a chained list; we will set up all but one entry in the + * first list (the last entry is saved for link information); + * otherwise, we don't have a chained list and we'll set up at each of + * the entries in the one list. + */ curr_sg = cp->SG; - chained = 0; - sg_index = 0; - scsi_for_each_sg(cmd, sg, use_sg, i) { - if (i == h->max_cmd_sg_entries - 1 && - use_sg > h->max_cmd_sg_entries) { - chained = 1; - curr_sg = h->cmd_sg_list[cp->cmdindex]; - sg_index = 0; - } + chained = use_sg > h->max_cmd_sg_entries; + sg_limit = chained ? h->max_cmd_sg_entries - 1 : use_sg; + last_sg = scsi_sg_count(cmd) - 1; + scsi_for_each_sg(cmd, sg, sg_limit, i) { hpsa_set_sg_descriptor(curr_sg, sg); curr_sg++; } + if (chained) { + /* + * Continue with the chained list. Set curr_sg to the chained + * list. Modify the limit to the total count less the entries + * we've already set up. Resume the scan at the list entry + * where the previous loop left off. + */ + curr_sg = h->cmd_sg_list[cp->cmdindex]; + sg_limit = use_sg - sg_limit; + for_each_sg(sg, sg, sg_limit, i) { + hpsa_set_sg_descriptor(curr_sg, sg); + curr_sg++; + } + } + /* Back the pointer up to the last entry and mark it as "last". */ - (--curr_sg)->Ext = cpu_to_le32(HPSA_SG_LAST); + (curr_sg - 1)->Ext = cpu_to_le32(HPSA_SG_LAST); if (use_sg + chained > h->maxSG) h->maxSG = use_sg + chained;