From mboxrd@z Thu Jan 1 00:00:00 1970 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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 EDB7BC2D0A3 for ; Mon, 9 Nov 2020 17:55:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 661732068D for ; Mon, 9 Nov 2020 17:55:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fieldses.org header.i=@fieldses.org header.b="wQOvZu2P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729976AbgKIRzx (ORCPT ); Mon, 9 Nov 2020 12:55:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729923AbgKIRzw (ORCPT ); Mon, 9 Nov 2020 12:55:52 -0500 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2291C0613CF; Mon, 9 Nov 2020 09:55:52 -0800 (PST) Received: by fieldses.org (Postfix, from userid 2815) id 9768B1C79; Mon, 9 Nov 2020 12:55:51 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 9768B1C79 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1604944551; bh=3bMCJ6oV4LyUEOFexrWIXMDsBYHsUZ6jBKyfSZ6GZAg=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=wQOvZu2Pbp/isw5mcfB+atX+QmeeTpreMzJ3DMd8juj/0xa56YlEgLBeUvU5TFw6k WzDLo+CJ4UO/9YBG/BZyTiJKhy8oyAgEwg2ANtGaFEndc7B8lPMXOgri+yb6l6A/zu WNNVrYzt9vcSVgrgapLVXd5sTKs3sGzlqQsPo9Ps= Date: Mon, 9 Nov 2020 12:55:51 -0500 To: Chuck Lever Cc: Trond Myklebust , Linux NFS Mailing List , "netdev@vger.kernel.org" Subject: Re: [PATCH RFC] SUNRPC: Use zero-copy to perform socket send operations Message-ID: <20201109175551.GC11144@fieldses.org> References: <160493771006.15633.8524084764848931537.stgit@klimt.1015granger.net> <9ce015245c916b2c90de72440a22f801142f2c6e.camel@hammerspace.com> <0313136F-6801-434F-8304-72B9EADD389E@oracle.com> <5056C7C7-7B26-4667-9691-D2F634C02FB1@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5056C7C7-7B26-4667-9691-D2F634C02FB1@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Nov 09, 2020 at 12:36:15PM -0500, Chuck Lever wrote: > > On Nov 9, 2020, at 12:32 PM, Trond Myklebust wrote: > > On Mon, 2020-11-09 at 12:12 -0500, Chuck Lever wrote: > >> I assume you mean the client side only. Those issues aren't a factor > >> on the server. Not setting SOCK_ZEROCOPY here should be enough to > >> prevent the use of zero-copy on the client. > >> > >> However, the client loses the benefits of sending a page at a time. > >> Is there a desire to remedy that somehow? > > > > What about splice reads on the server side? > > On the server, this path formerly used kernel_sendpages(), which I > assumed is similar to the sendmsg zero-copy mechanism. How does > kernel_sendpages() mitigate against page instability? We turn it off when gss integrity or privacy services is used, to prevent spurious checksum failures (grep for RQ_SPLICE_OK). But maybe that's not the only problematic case, I don't know. --b.