From nobody Sat Feb 7 15:10:11 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 014061553A2 for ; Mon, 29 Jul 2024 16:20:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722270055; cv=none; b=k8fnHcL8lhBFFdsbVYxIFsOaiwN2eUKto7/bN1UtDzzkWvkw8qqywsE04iPxVRmVse5/wQe4OQ4+7FE2I+7WDmmFRD7LzATftdMQl8V+kIyDtmOBFAVlnVxy8+hP+l/NPIVQJ5PFbBmnqEh9EKXaQxUusYEgYGTmkn6ghg8YA8Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722270055; c=relaxed/simple; bh=Q4gwfJJHtF30kFPtvejKeAQF831UgJF7V7gJtMLCh9U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AbS4AnUh+ZdNSPctMxr0o6PzHlKEOqUWdTS00OpYtUec4PPs/sQSqxEtfIeguUO2Rcw6GzYG39O/WhWxJRMF4G9uLxmp29V3TbMDptIkQCrXwhQl9Z8UM98VV96AI9pW2Fzka0Awj4E46imiX5gtV0UWhBa0INyWUe8RQuOZx54= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Jx7rGyTL; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Jx7rGyTL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722270053; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L/oVpDumRjUlX+aosidOXdQbOjRrDxev6yeZ4FfFDPg=; b=Jx7rGyTLewh99Mde2mA1g58imAJHaQJkPMZFNkIdTuh4In3NN3/SHrBZOpP6/m1bXW851e UM+/o74ChxVii4cmR2zw7HjYVG8I1iKJFbIFmUsLLSCvlLxm0mHWneiHBfLjuKZgK4bex7 eP3aPxLgnEBdueAh7sFUO0DsPzDFy7I= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-526-WgW1m07KO_iavDTjj_y9Sw-1; Mon, 29 Jul 2024 12:20:49 -0400 X-MC-Unique: WgW1m07KO_iavDTjj_y9Sw-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 73DCC1955D4C; Mon, 29 Jul 2024 16:20:45 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.42.28.216]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7174519560AE; Mon, 29 Jul 2024 16:20:39 +0000 (UTC) From: David Howells To: Christian Brauner , Steve French , Matthew Wilcox Cc: David Howells , Jeff Layton , Gao Xiang , Dominique Martinet , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Eric Van Hensbergen , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Steve French Subject: [PATCH 04/24] netfs: Record contention stats for writeback lock Date: Mon, 29 Jul 2024 17:19:33 +0100 Message-ID: <20240729162002.3436763-5-dhowells@redhat.com> In-Reply-To: <20240729162002.3436763-1-dhowells@redhat.com> References: <20240729162002.3436763-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" Record statistics for contention upon the writeback serialisation lock that prevents racing writeback calls from causing each other to interleave their writebacks. These can be viewed in /proc/fs/netfs/stats on the WbLock line, with skip=3DN indicating the number of non-SYNC writebacks skipped and wait= =3DN indicating the number of SYNC writebacks that waited. Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/netfs/internal.h | 2 ++ fs/netfs/stats.c | 5 +++++ fs/netfs/write_issue.c | 10 +++++++--- 3 files changed, 14 insertions(+), 3 deletions(-) diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h index 7773f3d855a9..9e6e0e59d7e4 100644 --- a/fs/netfs/internal.h +++ b/fs/netfs/internal.h @@ -117,6 +117,8 @@ extern atomic_t netfs_n_wh_upload_failed; extern atomic_t netfs_n_wh_write; extern atomic_t netfs_n_wh_write_done; extern atomic_t netfs_n_wh_write_failed; +extern atomic_t netfs_n_wb_lock_skip; +extern atomic_t netfs_n_wb_lock_wait; =20 int netfs_stats_show(struct seq_file *m, void *v); =20 diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c index 95ed2d2623a8..5fe1c396e24f 100644 --- a/fs/netfs/stats.c +++ b/fs/netfs/stats.c @@ -39,6 +39,8 @@ atomic_t netfs_n_wh_upload_failed; atomic_t netfs_n_wh_write; atomic_t netfs_n_wh_write_done; atomic_t netfs_n_wh_write_failed; +atomic_t netfs_n_wb_lock_skip; +atomic_t netfs_n_wb_lock_wait; =20 int netfs_stats_show(struct seq_file *m, void *v) { @@ -78,6 +80,9 @@ int netfs_stats_show(struct seq_file *m, void *v) atomic_read(&netfs_n_rh_rreq), atomic_read(&netfs_n_rh_sreq), atomic_read(&netfs_n_wh_wstream_conflict)); + seq_printf(m, "WbLock : skip=3D%u wait=3D%u\n", + atomic_read(&netfs_n_wb_lock_skip), + atomic_read(&netfs_n_wb_lock_wait)); return fscache_stats_show(m); } EXPORT_SYMBOL(netfs_stats_show); diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c index 9258d30cffe3..e7d4f39b8fdc 100644 --- a/fs/netfs/write_issue.c +++ b/fs/netfs/write_issue.c @@ -503,10 +503,14 @@ int netfs_writepages(struct address_space *mapping, struct folio *folio; int error =3D 0; =20 - if (wbc->sync_mode =3D=3D WB_SYNC_ALL) + if (!mutex_trylock(&ictx->wb_lock)) { + if (wbc->sync_mode =3D=3D WB_SYNC_NONE) { + netfs_stat(&netfs_n_wb_lock_skip); + return 0; + } + netfs_stat(&netfs_n_wb_lock_wait); mutex_lock(&ictx->wb_lock); - else if (!mutex_trylock(&ictx->wb_lock)) - return 0; + } =20 /* Need the first folio to be able to set up the op. */ folio =3D writeback_iter(mapping, wbc, NULL, &error);