From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conssluserg-06.nifty.com (conssluserg-06.nifty.com [210.131.2.91]) by sourceware.org (Postfix) with ESMTPS id 31710385840C for ; Sat, 11 Sep 2021 02:35:44 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 31710385840C Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=nifty.ne.jp Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=nifty.ne.jp Received: from Express5800-S70 (z221123.dynamic.ppp.asahi-net.or.jp [110.4.221.123]) (authenticated) by conssluserg-06.nifty.com with ESMTP id 18B2ZB3P013389 for ; Sat, 11 Sep 2021 11:35:11 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-06.nifty.com 18B2ZB3P013389 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.ne.jp; s=dec2015msa; t=1631327711; bh=lusukclj2gULOffhnIFt1CqGT/GLDrJLTiCbvQE0opM=; h=Date:From:To:Subject:In-Reply-To:References:From; b=T0tDDC9h1SSk2VMqeK1w2qN9JlmTWK27YbdT0tXs70OIYHbDIcWPjHd5nClFlTbrP UfQ6rhxbYYTXPMshByH+sqVAS39rcUkvFsldqdz0hgBlXWVKxIAJwedNT6DCPtd3pW /jRoWV6YQQaIkTuekU9JXPv25UPLxWTnP978m3bfMMH7sdoPXksG+MnePfIV1xp4et QYNIB+XLBpWWgBbkcBC2vbrAD9DyAQd7vBncNvY+1swgUa4HXYa0CGjz43RrPSmWPt drb74Q/kONEdjtQaMFxwn6WHTziKDqYSHi99M6C3IWXTB05HW9i0aBCoIooYbBSFcj mTnEkt2TmYmQA== X-Nifty-SrcIP: [110.4.221.123] Date: Sat, 11 Sep 2021 11:35:17 +0900 From: Takashi Yano To: cygwin-developers@cygwin.com Subject: Re: cygrunsrv + sshd + rsync = 20 times too slow -- throttled? Message-Id: <20210911113517.f74fc3ac1971bbf04c7a9bd1@nifty.ne.jp> In-Reply-To: References: <41A583E1-C8E7-42AB-9F24-EEC33A41EC60@house.org> <20210825201845.07b6400b79dc5558a7761efe@nifty.ne.jp> <20210826062934.54f2f2216021c095bb7ba13b@nifty.ne.jp> <3b560051-ab27-f392-ca4b-d1fd9b5733b0@cornell.edu> <20210827202440.47706fc2fc07c5e9a1bc0047@nifty.ne.jp> <20210907122631.65452be8d021ec72259431d5@nifty.ne.jp> <20210909124115.555c6be15d675500617d284a@nifty.ne.jp> <20210909170549.506cc3c1f6029d904fece6dd@nifty.ne.jp> <20210909211940.51ef391e27d43f0421962cb8@nifty.ne.jp> <20210909214246.cd1ff1a3062fea27e51ad4ae@nifty.ne.jp> <33386baf-3b2d-d57f-2ad3-1bd328ed7935@cornell.edu> <20210911075734.aaf37697ba7db2ad14d911a3@nifty.ne.jp> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.30; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-11.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin-developers@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Cygwin core component developers mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 11 Sep 2021 02:35:47 -0000 On Fri, 10 Sep 2021 22:17:21 -0400 Ken Brown wrote: > On 9/10/2021 6:57 PM, Takashi Yano wrote: > > On Fri, 10 Sep 2021 11:17:58 -0400 > > Ken Brown wrote: > >> I've rerun your test with the latest version, and the test results are similar. > >> I've also run a suite of fifo tests that I've accumulated, and they all pass > >> also, so I pushed your patch. > >> > >> I think we're in pretty good shape now. The only detail remaining, AFAIK, is > >> how to best avoid a deadlock if the pipe has been created by a non-Cygwin > >> process. I've proposed a timeout, but maybe there's a better idea. > > > > I am not pretty sure what is the problem, but is not the following > > patch enough? > > > > diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h > > index d309be2f7..13fba9a14 100644 > > --- a/winsup/cygwin/fhandler.h > > +++ b/winsup/cygwin/fhandler.h > > @@ -1205,6 +1205,7 @@ public: > > select_record *select_except (select_stuff *); > > char *get_proc_fd_name (char *buf); > > int open (int flags, mode_t mode = 0); > > + void open_setup (int flags); > > void fixup_after_fork (HANDLE); > > int dup (fhandler_base *child, int); > > int close (); > > diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc > > index 6994a5dce..d84e6ad84 100644 > > --- a/winsup/cygwin/fhandler_pipe.cc > > +++ b/winsup/cygwin/fhandler_pipe.cc > > @@ -191,6 +191,17 @@ out: > > return 0; > > } > > > > +void > > +fhandler_pipe::open_setup (int flags) > > +{ > > + fhandler_base::open_setup (flags); > > + if (get_dev () == FH_PIPER && !read_mtx) > > + { > > + SECURITY_ATTRIBUTES *sa = sec_none_cloexec (flags); > > + read_mtx = CreateMutexW (sa, FALSE, NULL); > > + } > > +} > > + > > off_t > > fhandler_pipe::lseek (off_t offset, int whence) > > { > > > > > > AFAIK, another problem remaining is: > > > > On Mon, 6 Sep 2021 14:49:55 +0200 > > Corinna Vinschen wrote: > >> - What about calling select for writing on pipes read by non-Cygwin > >> processes? In that case, we still can't rely on WriteQuotaAvailable, > >> just as before. > > This is the problem I was talking about. In this case the non-Cygwin process > might have a large pending read, so that the Cygwin process calling select on > the write side will see WriteQuotaAvailable == 0. This could lead to a deadlock > with the Cygwin process waiting for write ready while the non-Cygwin process is > blocked trying to read. Then, the above patch is for another issue. The problem happes when: 1) Start command prompt. 2) Run 'echo AAAAAAAAAAAA | \cygwin64\bin\cat This causes hang up in cat. In this case, pipe is created by cmd.exe. Therefore, read_mtx is not created. > My suggestion is that we impose a timeout in this situation, after which select > reports write ready. Keeping read handle in write pipe (Corinna's query_hdl) causes problem that write side cannot detect close on read side. Is it possible to open read handle temporally when pipe_data_available() is called? -- Takashi Yano