X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org CA8E33857C7C
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1635502584;
	bh=eghh5mey87KOucGBT6JU6Jth6Kve72yMIRFyxOWHUA0=;
	h=Date:To:Subject:In-Reply-To:References:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	From;
	b=XE924gb6fQ1IXHTEoZ1FNKulKrIlq2PtFhXIqgeAOiwY6kn5YiKpej+X05IC8FjIO
	NaHg41ofkmvI6b5hAWfeLxSijofNJqXOk+4REyI73/Qh/FbcUuVv/zV/p3XOPjJVdZ
	3dHwFQubF/xLwWUkXLplhcw/BWs8lrpFhOx/RcXo=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.1 sourceware.org 47F173858C39
DKIM-Filter:	OpenDKIM Filter v2.10.3 conssluserg-02.nifty.com 19TAEWWR002509
X-Nifty-SrcIP:	[110.4.221.123]
Date:	Fri, 29 Oct 2021 19:14:34 +0900
To:	cygwin AT cygwin DOT com
Subject:	Re: Curiosity about file access performance
Message-Id:	<20211029191434.737060387e2007319bcf3894@nifty.ne.jp>
In-Reply-To:	<00895c47-8df9-1f17-baac-0b3560de9d1c@cs.umass.edu>
References:	<00895c47-8df9-1f17-baac-0b3560de9d1c AT cs DOT umass DOT edu>
X-Mailer:	Sylpheed 3.7.0 (GTK+ 2.24.30; i686-pc-mingw32)
Mime-Version:	1.0
X-Spam-Status:	No, score=-5.5 required=5.0 tests=BAYES_00, DKIM_SIGNED,
	DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, 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 AT cygwin DOT com
X-Mailman-Version:	2.1.29
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Unsubscribe:	<https://cygwin.com/mailman/options/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
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:	Takashi Yano via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>
Errors-To:	cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com
Sender:	"Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

On Fri, 29 Oct 2021 10:35:08 +0100
Eliot Moss wrote:
> I think a lot of us know that fork() under Cygwin is slower than on Linux and
> have some grasp of why.  But I have noticed that file access is rather lower
> under Cygwin as well.  My "poster child" for this is running latex.  I am
> working on writing a book, which includes a huge number of LaTeX style files
> and such.  Under WSL1 (which has the same fork cost issues as Cygwin for
> similar reasons), reading the style files goes by in little more than the
> blink of an eye (about 1 sec), while on Cygwin it takes a little over 17 seconds.
> 
> The time to process the body of the book is 23 seconds under WSL1 and 35 under
> Cygwin.  So the total times are 53 seconds under Cygwin and 24 under WSL1.  I
> believe the LaTeX installations are the same versions, and I get the same
> outputs.  Both LaTeX's are 64 bit programs.  There is not much forking here
> (at least I don't believe there is, but maybe there is under the cover for
> doing things with pdf figures or something), but a fair amount of file I/O.
> 
> For many / most things, the Cygwin overhead is tolerable; for running this
> book, since I will be doing it over and over, it was worth investing in
> getting everything set up on WSL1.
> 
> But it got me wondering as to why?

Why do you think the cause is the file access performance?
I tested the file access speed using dd as follows.

In cygwin:
[yano AT Express5800-S70 ~]$ dd if=/dev/zero of=test.dat bs=1M count=500
500+0 records in
500+0 records out
524288000 bytes (524 MB, 500 MiB) copied, 0.186714 s, 2.8 GB/s
[yano AT Express5800-S70 ~]$ dd if=test.dat of=/dev/null bs=1M count=500
500+0 records in
500+0 records out
524288000 bytes (524 MB, 500 MiB) copied, 0.125709 s, 4.2 GB/s

In WSL1:
Express5800-S70:~> dd if=/dev/zero of=test.dat bs=1M count=500
500+0 records in
500+0 records out
524288000 bytes (524 MB, 500 MiB) copied, 0.301657 s, 1.7 GB/s
Express5800-S70:~> dd if=test.dat of=/dev/null bs=1M count=500
500+0 records in
500+0 records out
524288000 bytes (524 MB, 500 MiB) copied, 0.229617 s, 2.3 GB/s

The result shows the file access performance of cygwin is
better than WSL1.

I think the cause of your problem is something other than
file access performance.

-- 
Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>

-- 
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 -