X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 25E4F3858028
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1702880588;
	bh=epBCMPv2UC/S6kf8R3xsN7uzxqO6Qp36ANgE1ATUxAE=;
	h=References:In-Reply-To:Date:Subject:To:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	From;
	b=xoVS0+iOzOCGO7VNJtnlAKpq8PvnCootcwBqPyKVC/ZaT9J3bTCRslyC8ARPUl2GR
	OkKNoiDa7+urogGvRq65vYqqgd7Zp01BWgYI2PNxeQ4s/aguaRyfICBoR2M8hW4tuo
	4nvWhWnMYWqK25cYDTivEoByqx6SJqdIPFd/kn08=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org ABD863858435
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org ABD863858435
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1702880574; cv=none;
	b=CxENqx/ykEK9wYH90Vm2DxTD0OtKz8waNftbijD5TsmeVn8s/XArWjSQVnJqVhQkQT/DpofpNeeFGiHtzSLYlry9/eRHwmeUwhLXq80opUsWn4sQg3HtTg17MHKp9dW6RTg7r//U2Tjxoo1GSyx0xepzxCVoi43RmRTSCLaJKGM=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1702880574; c=relaxed/simple;
	bh=ZwlO6jRRUPgG8mwf34H2pfVlNSkDMDOq6oCnu6gwNfQ=;
	h=DKIM-Signature:MIME-Version:From:Date:Message-ID:Subject:To;
	b=BFbvZW0yOGTO1xYXiFROZtNDZ6PdyY/HBB2dG/kBHwXXH5PFU8V6lOeSxZqerpiQ8dxzzWTKHzsTDjZYl1hMYMHqc/zbNcDEt2DtDCGZbvRyg6Yi4WNg3L+25QBopJVO/G0VKsgDc3BvOS9kdOTbKgdQL7fd7QhMBHKX/pCXQ5o=
ARC-Authentication-Results:	i=1; server2.sourceware.org
X-Google-DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed;
	d=1e100.net; s=20230601; t=1702880570; x=1703485370;
	h=to:subject:message-id:date:from:in-reply-to:references:mime-version
	:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to;
	bh=XHXYGuhh6XYay6HrAY3G7geks+0g+1i7WuFOOFQQBVY=;
	b=EXhRO57Sb0TfH87Nkv7eo+OXfiC5LUha/QM4dVP9qdh02KckbKHccEva+WZmx1LKW+
	k357FxvTg59w7YWqyjyiSLuINp1fW++EnDy1u6zj+NirAxcq6lb01mkxyQkg1mex38yE
	/Kkfjeb7B5C+vEkP/JJjRDhi2LHFTnui+8JnJlv4dAl2qpDSRrkXXNDlP0bL7AsNWQyM
	zY40faXmpCHiAv/f9ouT5wnhlFT+1H0+uW3VXLr/lkWXzOg5VECMKdRnmOSmDKViv6kM
	ja5QIsfhVQkZgqUP5p4PlESuMtnCtsna7js6EEmMx2+Rgbb/xStXr7DW+KnOIrZ2BIq8
	4WIg==
X-Gm-Message-State:	AOJu0Yy8K6zrR5Gji1Vn33dciWH+Tz2UsGYnGSRdgCYEW+h0adbMeCvZ
	htyIN4TxQNHpnCnukXWbKgXlOEr37dcbZ0Lr9bIHZlBF
X-Google-Smtp-Source:	AGHT+IEPFLHnGWrnABwe6LS1hINau7khCTHW7gBUHli6yt+4gFHN3cnO269GoAEBarRi7qsCTyiO5NoVT9dQry03UWM=
X-Received:	by 2002:a2e:be8c:0:b0:2c9:fa34:332d with SMTP id
	a12-20020a2ebe8c000000b002c9fa34332dmr7282612ljr.12.1702880570421; Sun, 17
	Dec 2023 22:22:50 -0800 (PST)
MIME-Version:	1.0
References:	<CAAvCNcBZGepZMP9Q0D5ua+6ACftDOQEriqnuCbwg6umBPUA72Q AT mail DOT gmail DOT com>
In-Reply-To:	<CAAvCNcBZGepZMP9Q0D5ua+6ACftDOQEriqnuCbwg6umBPUA72Q@mail.gmail.com>
Date:	Mon, 18 Dec 2023 07:22:24 +0100
Message-ID:	<CAAvCNcB0_0ZeujP23QZFZaDvVTh5rxbXJw4FP6uXNPErCgdZ2w@mail.gmail.com>
Subject:	Re: Catastrophic Cygwin find . -ls, grep performance on samba share
	compared to WSL&Linux
To:	cygwin AT cygwin DOT com
X-Spam-Status:	No, score=0.3 required=5.0 tests=BAYES_00, DKIM_SIGNED,
	DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,
	SPF_HELO_NONE, SPF_PASS, TXREP,
	T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version:	SpamAssassin 3.4.6 (2021-04-09) on
	server2.sourceware.org
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.30
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From:	Dan Shelton via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Dan Shelton <dan DOT f DOT shelton AT gmail DOT com>
Sender:	"Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

On Wed, 6 Dec 2023 at 05:08, Dan Shelton <dan DOT f DOT shelton AT gmail DOT com> wrote:
>
> Hello!
> I am unhappy to report a severe performance issue with find -ls, ls -R
> and grep -r, with Cygwin 3.4.9 and Cygwin 3.5.0 when samba shares are
> involved.
>
> Imagine a directory with 256 subdirs, and each has 256 files per
> subdir, all on a samba share, samba server is on Linux with tmpfs.
>
> mkdir dir1
> for ((i=0;i<256;i++)) ; do
>     mkdir "dir1/subdir$i"
>     for ((j=0; j < 256;j++));do
>         echo  "j=$j" >"dir1/subdir$i/j$j.txt"
>     done
> done
>
> Time comparisations then show a dramatic difference, Debian Linux
> accessing the samba share, WSL accessing the samba share, and Cygwin
> accessing the samba share:
> 1. time find . >/dev/null
> Cygwin 86 seconds
> WSL 23 seconds
> Debian 19 seconds
>
> 2. time find . -ls >/dev/null
> Cygwin 129 seconds
> WSL 38 seconds
> Debian 32 seconds
>
> 3. time grep -r -E NOMATCH 2>/dev/null
> Cygwin 390 seconds
> WSL 144 seconds
> Debian 141 seconds
>
> So where does the bad Cygwin performance come from? Virus checker,
> memory compression and other Windows services known to interfere with
> benchmarking are OFF.
>
> But the network trace shows a dramatic difference: While Debian and
> WSL open files only once, the Cygwin run spends lots of network
> traffic checking whether the txt files are txt.lnk, txt,bat.lnk and so
> on, all non existent files.
>
> Why does that happen?

It would be nice if someone from the Cygwin authors could assist me in
figuring out why this happens.

My working theory is that the extra file and dir lookup calls are for
soft- and hardlink emulation for file systems which do not have soft-
or hardlinks?
If this is correct, then a fix might be to 1) determinate the
filesystem type (cached, per process lifetime in absence of
/etc/mnttab) and its boundaries (mount point, and whether other muont
points are below it) 2) Only use the emulation for FAT filesystems,
and for NTFS, REFS, SMBFS the native filesystem link is used.

Help!

Dan
-- 
Dan Shelton - Cluster Specialist Win/Lin/Bsd

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

- Raw text -