From patchwork Wed Sep 15 22:32:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 512681 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBE8DC433EF for ; Wed, 15 Sep 2021 22:41:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F79660FED for ; Wed, 15 Sep 2021 22:41:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232977AbhIOWmd (ORCPT ); Wed, 15 Sep 2021 18:42:33 -0400 Received: from smtp.infotech.no ([82.134.31.41]:36524 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232852AbhIOWma (ORCPT ); Wed, 15 Sep 2021 18:42:30 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id 24FF82041F1; Thu, 16 Sep 2021 00:33:13 +0200 (CEST) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id FAPDQzeGQy17; Thu, 16 Sep 2021 00:33:11 +0200 (CEST) Received: from xtwo70.bingwo.ca (host-45-78-207-107.dyn.295.ca [45.78.207.107]) by smtp.infotech.no (Postfix) with ESMTPA id A4B462041CF; Thu, 16 Sep 2021 00:33:07 +0200 (CEST) From: Douglas Gilbert To: linux-scsi@vger.kernel.org Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, hare@suse.de, Damien.LeMoal@wdc.com, Hannes Reinecke Subject: [PATCH v20 08/46] sg: speed sg_poll and sg_get_num_waiting Date: Wed, 15 Sep 2021 18:32:27 -0400 Message-Id: <20210915223305.256429-9-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210915223305.256429-1-dgilbert@interlog.com> References: <20210915223305.256429-1-dgilbert@interlog.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Track the number of submitted and waiting (for read/receive) requests on each file descriptor with two atomic integers. This speeds sg_poll() and ioctl(SG_GET_NUM_WAITING) which are oft used with the asynchronous (non-blocking) interfaces. Reviewed-by: Hannes Reinecke Signed-off-by: Douglas Gilbert --- drivers/scsi/sg.c | 54 +++++++++++++++++++++++------------------------ 1 file changed, 27 insertions(+), 27 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index bf16b7c9639c..0d112272a667 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -142,6 +142,8 @@ struct sg_fd { /* holds the state of a file descriptor */ struct mutex f_mutex; /* protect against changes in this fd */ int timeout; /* defaults to SG_DEFAULT_TIMEOUT */ int timeout_user; /* defaults to SG_DEFAULT_TIMEOUT_USER */ + atomic_t submitted; /* number inflight or awaiting read */ + atomic_t waiting; /* number of requests awaiting read */ struct sg_scatter_hold reserve; /* buffer for this file descriptor */ struct list_head rq_list; /* head of request list */ struct fasync_struct *async_qp; /* used by asynchronous notification */ @@ -683,6 +685,8 @@ sg_common_write(struct sg_fd *sfp, struct sg_request *srp, else at_head = 1; + if (!blocking) + atomic_inc(&sfp->submitted); srp->rq->timeout = timeout; kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */ blk_execute_rq_nowait(NULL, srp->rq, at_head, sg_rq_end_io); @@ -1105,14 +1109,7 @@ sg_ioctl_common(struct file *filp, struct sg_device *sdp, struct sg_fd *sfp, read_unlock_irqrestore(&sfp->rq_list_lock, iflags); return put_user(-1, ip); case SG_GET_NUM_WAITING: - read_lock_irqsave(&sfp->rq_list_lock, iflags); - val = 0; - list_for_each_entry(srp, &sfp->rq_list, entry) { - if ((1 == srp->done) && (!srp->sg_io_owned)) - ++val; - } - read_unlock_irqrestore(&sfp->rq_list_lock, iflags); - return put_user(val, ip); + return put_user(atomic_read(&sfp->waiting), ip); case SG_GET_SG_TABLESIZE: return put_user(sdp->max_sgat_elems, ip); case SG_SET_RESERVED_SIZE: @@ -1260,35 +1257,26 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) return scsi_ioctl(sdp->device, NULL, filp->f_mode, cmd_in, p); } +/* + * Implements the poll(2) system call for this driver. Returns various EPOLL* + * flags OR-ed together. + */ static __poll_t sg_poll(struct file *filp, poll_table * wait) { __poll_t p_res = 0; struct sg_fd *sfp = filp->private_data; - struct sg_request *srp; - int count = 0; - unsigned long iflags; - if (!sfp) - return EPOLLERR; poll_wait(filp, &sfp->read_wait, wait); - read_lock_irqsave(&sfp->rq_list_lock, iflags); - list_for_each_entry(srp, &sfp->rq_list, entry) { - /* if any read waiting, flag it */ - if (p_res == 0 && srp->done == 1 && !srp->sg_io_owned) - p_res = EPOLLIN | EPOLLRDNORM; - ++count; - } - read_unlock_irqrestore(&sfp->rq_list_lock, iflags); + if (atomic_read(&sfp->waiting) > 0) + p_res = EPOLLIN | EPOLLRDNORM; - if (sfp->parentdp && SG_IS_DETACHING(sfp->parentdp)) { + if (unlikely(SG_IS_DETACHING(sfp->parentdp))) p_res |= EPOLLHUP; - } else if (!sfp->cmd_q) { - if (count == 0) - p_res |= EPOLLOUT | EPOLLWRNORM; - } else if (count < SG_MAX_QUEUE) { + else if (likely(sfp->cmd_q)) + p_res |= EPOLLOUT | EPOLLWRNORM; + else if (atomic_read(&sfp->submitted) == 0) p_res |= EPOLLOUT | EPOLLWRNORM; - } SG_LOG(3, sfp, "%s: p_res=0x%x\n", __func__, (__force u32)p_res); return p_res; } @@ -1473,6 +1461,8 @@ sg_rq_end_io(struct request *rq, blk_status_t status) /* Rely on write phase to clean out srp status values, so no "else" */ + if (!srp->sg_io_owned) + atomic_inc(&sfp->waiting); /* * Free the request as soon as it is complete so that its resources * can be reused without waiting for userspace to read() the @@ -1915,6 +1905,10 @@ sg_finish_rem_req(struct sg_request *srp) SG_LOG(4, sfp, "%s: srp=0x%p%s\n", __func__, srp, (srp->res_used) ? " rsv" : ""); + if (!srp->sg_io_owned) { + atomic_dec(&sfp->submitted); + atomic_dec(&sfp->waiting); + } if (srp->bio) ret = blk_rq_unmap_user(srp->bio); @@ -2208,6 +2202,9 @@ sg_add_sfp(struct sg_device *sdp) sfp->cmd_q = SG_DEF_COMMAND_Q; sfp->keep_orphan = SG_DEF_KEEP_ORPHAN; sfp->parentdp = sdp; + atomic_set(&sfp->submitted, 0); + atomic_set(&sfp->waiting, 0); + write_lock_irqsave(&sdp->sfd_lock, iflags); if (SG_IS_DETACHING(sdp)) { write_unlock_irqrestore(&sdp->sfd_lock, iflags); @@ -2578,6 +2575,9 @@ sg_proc_debug_helper(struct seq_file *s, struct sg_device *sdp) seq_printf(s, " cmd_q=%d f_packid=%d k_orphan=%d closed=0\n", (int) fp->cmd_q, (int) fp->force_packid, (int) fp->keep_orphan); + seq_printf(s, " submitted=%d waiting=%d\n", + atomic_read(&fp->submitted), + atomic_read(&fp->waiting)); list_for_each_entry(srp, &fp->rq_list, entry) { hp = &srp->header; new_interface = (hp->interface_id == '\0') ? 0 : 1;