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Diffstat (limited to 'winsup/doc/faq-using.xml')
| -rw-r--r-- | winsup/doc/faq-using.xml | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/winsup/doc/faq-using.xml b/winsup/doc/faq-using.xml index 4dc462a..111702c 100644 --- a/winsup/doc/faq-using.xml +++ b/winsup/doc/faq-using.xml @@ -855,6 +855,11 @@ possible to preset the sparse attribute with <literal>chattr</literal>. ---a-S-------- 2/is_sparse ---a-S-------- 2/maybe_sparse ---a-S-------- 2/not_sparse + $ lssparse -H 0/is_sparse # from cygutils-extra package + Hole range[1]: offset=0x0, length=0x100000 + Data range[2]: offset=0x100000, length=0x4 + $ lssparse -H 0/not_sparse + Data range[1]: offset=0x0, length=0x100004 </screen> <para>With <literal>sparse</literal> mount option or a SSD, all <literal>?/maybe_sparse</literal> files would be sparse. @@ -956,6 +961,26 @@ 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. |