https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=ac28fce85cc4d8f85c2cf10bb52d39f33ec38ed6
commit ac28fce85cc4d8f85c2cf10bb52d39f33ec38ed6
Author: Christian Franke <christian.fra...@t-online.de>
Date: Sat Mar 29 16:34:33 2025 +0100
Cygwin: faq: add test of fork/exec slowdown by anti-virus
Signed-off-by: Christian Franke <christian.fra...@t-online.de>
Diff:
---
winsup/doc/faq-using.xml | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/winsup/doc/faq-using.xml b/winsup/doc/faq-using.xml
index 4dc462a0a..e5e4479f5 100644
--- a/winsup/doc/faq-using.xml
+++ b/winsup/doc/faq-using.xml
@@ -956,6 +956,26 @@ contents are exempt from scanning. In a default
installation, this
would be <literal>C:\cygwin\bin</literal>. Obviously, this could be
exploited by a hostile non-Cygwin program, so do this at your own risk.
</para>
+<para>Anti-virus software typically reduce the speed of Windows
+<literal>CreateProcess</literal> calls which are used by Cygwin to provide
+<literal>fork()</literal> and <literal>exec()</literal>. This in particular
+slows down shell scripts. In the simple speed test shown below, the first
+column shows the number of <literal>date</literal> commands run per second.
+Anti-virus was turned off at the line marked with <literal>***</literal>.
+</para>
+<screen>
+ bash$ while :; do date +%s; done | uniq -c
+ ...
+ 122 1741712430
+ 118 1741712431
+ 118 1741712432
+ 121 1741712433
+ 142 1741712434 ***
+ 140 1741712435
+ 141 1741712436
+ 144 1741712437
+ ...
+</screen>
<para>See also <xref linkend="faq.using.bloda"></xref>
for a list of applications that have been known, at one time or another, to
interfere with the normal functioning of Cygwin.
