runshell LD_HWCAP_MASK=0 optimisation

Build/LinuxMkLibs.hs

@@ -24,7 +24,7 @@ import Utility.Path
 import Utility.FileMode
 import Utility.CopyFile
 
-mklibs :: FilePath -> a -> IO ()
+mklibs :: FilePath -> a -> IO Bool
 mklibs top _installedbins = do
 	fs <- dirContentsRecursive top
 	exes <- filterM checkExe fs
@@ -48,6 +48,19 @@ mklibs top _installedbins = do
 	let linker = Prelude.head linkers
 	mapM_ (installLinkerShim top linker) exes
 	
+	return (any hwcaplibdir libdirs)
+  where
+	-- hwcap lib dirs are things like foo/tls and foo/x86.
+	-- Hard to know if a directory is, so this is a heuristic
+	-- looking for things that are certianly not. If this heuristic
+	-- fails, a minor optimisation will not happen, but there will be
+	-- no bad results.
+	hwcaplibdir d = not $ or
+		[ "lib" == takeFileName d
+		-- eg, "lib/x86_64-linux-gnu"
+		, "-linux-" `isInfixOf` takeFileName d
+		]
+
 {- If there are two libdirs that are the same except one is in
  - usr/lib and the other is in lib/, move the contents of the usr/lib one
  - into the lib/ one. This reduces the number of directories the linker

Build/OSXMkLibs.hs

@@ -31,8 +31,10 @@ import qualified Data.Set as S
 
 type LibMap = M.Map FilePath String
 
-mklibs :: FilePath -> M.Map FilePath FilePath -> IO ()
-mklibs appbase installedbins = mklibs' appbase installedbins [] [] M.empty
+mklibs :: FilePath -> M.Map FilePath FilePath -> IO Bool
+mklibs appbase installedbins = do
+	mklibs' appbase installedbins [] [] M.empty
+	return True
 
 {- Recursively find and install libs, until nothing new to install is found. -}
 mklibs' :: FilePath -> M.Map FilePath FilePath -> [FilePath] -> [(FilePath, FilePath)] -> LibMap -> IO ()

Build/Standalone.hs

@@ -152,13 +152,22 @@ installLocales _ = return ()
 installLocales topdir = cp "/usr/share/i18n" (topdir </> "i18n")
 #endif
 
-installWrapper :: FilePath -> FilePath -> IO ()
+installSkel :: FilePath -> FilePath -> IO ()
 #ifdef darwin_HOST_OS
-installWrapper topdir basedir = do
+installSkel topdir basedir = do
 	removeDirectoryRecursive basedir
-	createDirectoryIfMissing True (takeDirectory basedir)
 	unlessM (boolSystem "cp" [Param "-R", File "standalone/osx/git-annex.app", File basedir]) $
 		error "cp failed"
+#else
+installSkel topdir _basedir = do
+	removeDirectoryRecursive topdir
+	unlessM (boolSystem "cp" [Param "-R", File "standalone/linux/skel", File topdir]) $
+		error "cp failed"
+#endif
+
+installSkelRest :: FilePath -> FilePath -> Bool -> IO ()
+#ifdef darwin_HOST_OS
+installSkelRest topdir basedir _hwcaplibs = do
 	plist <- lines <$> readFile "standalone/osx/Info.plist.template"
 	version <- getVersion
 	writeFile (basedir </> "Contents" </> "Info.plist")
@@ -166,11 +175,7 @@ installWrapper topdir basedir = do
   where
 	expandversion v l = replace "GIT_ANNEX_VERSION" v l
 #else
-installWrapper topdir _basedir = do
-	removeDirectoryRecursive topdir
-	createDirectoryIfMissing True (takeDirectory topdir)
-	unlessM (boolSystem "cp" [Param "-R", File "standalone/linux/skel", File topdir]) $
-		error "cp failed"
+installSkelRest topdir _basedir hwcaplibs = do
 	runshell <- lines <$> readFile "standalone/linux/skel/runshell"
 	-- GIT_ANNEX_PACKAGE_INSTALL can be set by a distributor and
 	-- runshell will be modified
@@ -180,6 +185,12 @@ installWrapper topdir _basedir = do
 	modifyFileMode (topdir </> "runshell") (addModes executeModes)
   where
 	expandrunshell (Just gapi) l@"GIT_ANNEX_PACKAGE_INSTALL=" = l ++ gapi
+	-- This is an optimisation, that avoids the linker looking in
+	-- several directories for hwcap optimised libs, when there are
+	-- none.
+	expandrunshell _ l@"LD_HWCAP_MASK=" = l ++ if not hwcaplibs
+		then "0"
+		else ""
 	expandrunshell _ l = l
 #endif
 
@@ -203,11 +214,12 @@ main :: IO ()
 main = getArgs >>= go
   where
 	go (topdir:basedir:[]) = do
-		installWrapper topdir basedir
+		installSkel topdir basedir
 		installGitAnnex topdir
 		installedbins <- installBundledPrograms topdir
 		installGitLibs topdir
 		installMagic topdir
 		installLocales topdir
-		mklibs topdir installedbins
+		hwcaplibs <- mklibs topdir installedbins
+		installSkelRest topdir basedir hwcaplibs
 	go _ = error "specify topdir and basedir"

doc/todo/may_be___40__again__41___to_prelink_or_somehow_avoid_all_the_failing_opens__63__.mdwn

@@ -61,3 +61,5 @@ git annex build: 8.20200617+git192-g5849bd634-1~ndall+1
 
 [[!meta author=yoh]]
 [[!tag projects/datalad]]
+
+> [[done]] --[[Joey]]

doc/todo/may_be___40__again__41___to_prelink_or_somehow_avoid_all_the_failing_opens__63__/comment_19_13b21a0523b8837f4e27bb78e35ad5e0._comment

@@ -0,0 +1,23 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 19"""
+ date="2020-08-03T18:16:50Z"
+ content="""
+Implemented the `LD_HWCAP_MASK=0` optimisation, which left only these:
+
+	strace -f ./git-annex version 2>&1 | grep ENOENT | grep openat
+	openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/tls/x86_64/libm.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+	openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/tls/libm.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+	openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/x86_64/libm.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+	[pid 697752] openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/tls/x86_64/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+	[pid 697752] openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/tls/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+	[pid 697752] openat(AT_FDCWD, "/home/joey/src/git-annex/tmp/git-annex.linux//lib/x86_64-linux-gnu/x86_64/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
+
+There are more failed opens now for locale files for commands like
+grep when running it than there are for libraries. So, no need to
+consider further prelinking.
+
+I think that rewriting runshell in C would be the
+logical next choice, but dunno if it would speed it up by enough to be 
+worth the effort. So I'm going to close this now.
+"""]]

standalone/linux/skel/runshell

@@ -241,6 +241,9 @@ else
 	cmd=sh
 fi
 
+LD_HWCAP_MASK=
+export LD_HWCAP_MASK
+
 if [ -n "${orig_IFS}" ]; then
 	IFS="${orig_IFS}"
 	export IFS