From patchwork Mon Jul 5 11:13:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Schoenebeck X-Patchwork-Id: 12358921 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C929EC07E99 for ; Mon, 5 Jul 2021 11:57:58 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F9EF61370 for ; Mon, 5 Jul 2021 11:57:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F9EF61370 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:33952 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m0NEb-0001Q4-MT for qemu-devel@archiver.kernel.org; Mon, 05 Jul 2021 07:57:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33436) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <8d6cb100731c4d28535adbf2a3c2d1f29be3fef4@lizzy.crudebyte.com>) id 1m0NDO-0007nt-N4 for qemu-devel@nongnu.org; Mon, 05 Jul 2021 07:56:42 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:45851) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <8d6cb100731c4d28535adbf2a3c2d1f29be3fef4@lizzy.crudebyte.com>) id 1m0NDM-0006mm-SM for qemu-devel@nongnu.org; Mon, 05 Jul 2021 07:56:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=oqfP9fRU/7pe1i5RUiFmMbCPfg8ll6ihKFEWlWmJnn8=; b=JZymd KikFN4mLW296tg8XSm9wrfAPnn3Ql3YeM9IMvXeBlchyil1louf17YPYeMHHvCkN6dI1B+Nz75hZJ TKEEhxMW/FqwGQ+bof97hLkQ38hrd1EfrGHI7oHkBru+HTBo+GwVmUgE2pcm/V1yR4vRD5b8naso9 lc+iPlirxWSzsw370X8YVDkHDIsLvpBaEkVwJ/+xgD+I3auhL5zHXgCXmbdSLCB6Vy2hgH6pqoQv3 ejpN0IKx1Th2jKNMidusdTSIfteJUNkRewBQH1D0RCdgysMfStf/n+ydyWr/OtuDyG6v7SaEmxGPe BWlrKzttmL+bUe9dStVAe4lHFHgNA==; Message-Id: <8d6cb100731c4d28535adbf2a3c2d1f29be3fef4.1625483630.git.qemu_oss@crudebyte.com> In-Reply-To: References: From: Christian Schoenebeck Date: Mon, 05 Jul 2021 13:13:51 +0200 Subject: [PULL 8/8] 9pfs: reduce latency of Twalk To: qemu-devel@nongnu.org, Peter Maydell Cc: Greg Kurz Received-SPF: none client-ip=91.194.90.13; envelope-from=8d6cb100731c4d28535adbf2a3c2d1f29be3fef4@lizzy.crudebyte.com; helo=lizzy.crudebyte.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" As with previous performance optimization on Treaddir handling; reduce the overall latency, i.e. overall time spent on processing a Twalk request by reducing the amount of thread hops between the 9p server's main thread and fs worker thread(s). In fact this patch even reduces the thread hops for Twalk handling to its theoritical minimum of exactly 2 thread hops: main thread -> fs worker thread -> main thread This is achieved by doing all the required fs driver tasks altogether in a single v9fs_co_run_in_worker({ ... }); code block. Signed-off-by: Christian Schoenebeck Reviewed-by: Greg Kurz Message-Id: <1a6701674afc4f08d40396e3aa2631e18a4dbb33.1622821729.git.qemu_oss@crudebyte.com> --- hw/9pfs/9p.c | 89 +++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 70 insertions(+), 19 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 7be07f2d68..2815257f42 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1705,9 +1705,9 @@ static void coroutine_fn v9fs_walk(void *opaque) int name_idx; V9fsQID *qids = NULL; int i, err = 0; - V9fsPath dpath, path; + V9fsPath dpath, path, *pathes = NULL; uint16_t nwnames; - struct stat stbuf; + struct stat stbuf, fidst, *stbufs = NULL; size_t offset = 7; int32_t fid, newfid; V9fsString *wnames = NULL; @@ -1733,6 +1733,8 @@ static void coroutine_fn v9fs_walk(void *opaque) if (nwnames) { wnames = g_new0(V9fsString, nwnames); qids = g_new0(V9fsQID, nwnames); + stbufs = g_new0(struct stat, nwnames); + pathes = g_new0(V9fsPath, nwnames); for (i = 0; i < nwnames; i++) { err = pdu_unmarshal(pdu, offset, "s", &wnames[i]); if (err < 0) { @@ -1753,39 +1755,85 @@ static void coroutine_fn v9fs_walk(void *opaque) v9fs_path_init(&dpath); v9fs_path_init(&path); + /* + * Both dpath and path initially point to fidp. + * Needed to handle request with nwnames == 0 + */ + v9fs_path_copy(&dpath, &fidp->path); + v9fs_path_copy(&path, &fidp->path); - err = v9fs_co_lstat(pdu, &fidp->path, &stbuf); + /* + * To keep latency (i.e. overall execution time for processing this + * Twalk client request) as small as possible, run all the required fs + * driver code altogether inside the following block. + */ + v9fs_co_run_in_worker({ + if (v9fs_request_cancelled(pdu)) { + err = -EINTR; + break; + } + err = s->ops->lstat(&s->ctx, &dpath, &fidst); + if (err < 0) { + err = -errno; + break; + } + stbuf = fidst; + for (name_idx = 0; name_idx < nwnames; name_idx++) { + if (v9fs_request_cancelled(pdu)) { + err = -EINTR; + break; + } + if (!same_stat_id(&pdu->s->root_st, &stbuf) || + strcmp("..", wnames[name_idx].data)) + { + err = s->ops->name_to_path(&s->ctx, &dpath, + wnames[name_idx].data, &path); + if (err < 0) { + err = -errno; + break; + } + if (v9fs_request_cancelled(pdu)) { + err = -EINTR; + break; + } + err = s->ops->lstat(&s->ctx, &path, &stbuf); + if (err < 0) { + err = -errno; + break; + } + stbufs[name_idx] = stbuf; + v9fs_path_copy(&dpath, &path); + v9fs_path_copy(&pathes[name_idx], &path); + } + } + }); + /* + * Handle all the rest of this Twalk request on main thread ... + */ if (err < 0) { goto out; } - err = stat_to_qid(pdu, &stbuf, &qid); + + err = stat_to_qid(pdu, &fidst, &qid); if (err < 0) { goto out; } + stbuf = fidst; - /* - * Both dpath and path initially poin to fidp. - * Needed to handle request with nwnames == 0 - */ + /* reset dpath and path */ v9fs_path_copy(&dpath, &fidp->path); v9fs_path_copy(&path, &fidp->path); + for (name_idx = 0; name_idx < nwnames; name_idx++) { if (!same_stat_id(&pdu->s->root_st, &stbuf) || - strcmp("..", wnames[name_idx].data)) { - err = v9fs_co_name_to_path(pdu, &dpath, wnames[name_idx].data, - &path); - if (err < 0) { - goto out; - } - - err = v9fs_co_lstat(pdu, &path, &stbuf); - if (err < 0) { - goto out; - } + strcmp("..", wnames[name_idx].data)) + { + stbuf = stbufs[name_idx]; err = stat_to_qid(pdu, &stbuf, &qid); if (err < 0) { goto out; } + v9fs_path_copy(&path, &pathes[name_idx]); v9fs_path_copy(&dpath, &path); } memcpy(&qids[name_idx], &qid, sizeof(qid)); @@ -1821,9 +1869,12 @@ out_nofid: if (nwnames && nwnames <= P9_MAXWELEM) { for (name_idx = 0; name_idx < nwnames; name_idx++) { v9fs_string_free(&wnames[name_idx]); + v9fs_path_free(&pathes[name_idx]); } g_free(wnames); g_free(qids); + g_free(stbufs); + g_free(pathes); } }