[PATCH] improve performance of stat() operations (e.g. ls -lR)

[PATCH] improve performance of stat() operations (e.g. ls -lR)

[Don Bowman]

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The attached patch adds a new CYGWIN environment variable, statquery. This
causes stat() to use set_query_open(TRUE) all the time, which
dramatically improves the performance on e.g. ls -lR operations or
configure.
For example, an ls -lR of the 'ntop' distribution goes from 34seconds
to 2seconds on my computer on a local filesystem. The actual change
is extremely trivial.



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--- src/winsup/cygwin/environ.cc	2002-05-24 22:22:50.000000000 -0400
+++ src-new/winsup/cygwin/environ.cc	2002-05-26 16:23:31.000000000 -0400
@@ -36,6 +36,7 @@ extern BOOL allow_winsymlinks;
 extern BOOL strip_title_path;
 extern int pcheck_case;
 extern int subauth_id;
+extern BOOL stat_open_noread;
 BOOL reset_com = FALSE;
 static BOOL envcache = TRUE;
 
@@ -525,6 +526,7 @@ static struct parse_thing
   {"title", {&display_title}, justset, NULL, {{FALSE}, {TRUE}}},
   {"tty", {NULL}, set_process_state, NULL, {{0}, {PID_USETTY}}},
   {"winsymlinks", {&allow_winsymlinks}, justset, NULL, {{FALSE}, {TRUE}}},
+  {"statquery", {&stat_open_noread}, justset, NULL, {{FALSE},{TRUE}}},
   {NULL, {0}, justset, 0, {{0}, {0}}}
 };
 
--- src/winsup/cygwin/fhandler_disk_file.cc	2002-05-24 01:44:10.000000000 -0400
+++ src-new/winsup/cygwin/fhandler_disk_file.cc	2002-05-26 16:05:46.000000000 -0400
@@ -31,6 +31,8 @@ details. */
 #define _COMPILING_NEWLIB
 #include <dirent.h>
 
+BOOL stat_open_noread;
+
 static int
 num_entries (const char *win32_name)
 {
@@ -72,7 +74,7 @@ fhandler_disk_file::fstat (struct __stat
   if (!pc)
     return fstat_helper (buf);
 
-  if ((oret = open (pc, open_flags, 0)))
+  if (!stat_open_noread && (oret = open (pc, open_flags, 0)))
     /* ok */;
   else
     {
--- src/winsup/cygwin/ChangeLog	2002-05-24 22:22:50.000000000 -0400
+++ src-new/winsup/cygwin/ChangeLog	2002-05-26 17:29:11.000000000 -0400
@@ -1,3 +1,12 @@
+2002-05-26  Don Bowman  <don@sandvine.com>
+
+	* Add new CYGWIN option, 'statquery', which causes the
+	stat() call to use the set_query_open(TRUE) all the time.
+	This significantly improves performance on e.g. ls -lR 
+	operation. It would appear the CreateFile() on windows
+	reads a good chunk of the file when called for reading,
+	which isn't needed by stat().
+
 2002-05-24  Christopher Faylor  <cgf@redhat.com>
 
 	Remove unneeded sync.h, where appropriate, throughout.


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Re: [PATCH] improve performance of stat() operations (e.g. ls -lR)

[Scott Evans]

Yeah!  Er, not that I've tried the patch, but if this works well
it could be huge... visions of XEmacs/Cygwin performing on par with
native Win32 XEmacs.



scott



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