Re: "ls -l": Avoid unnecessary getxattr() overhead

[Jim Meyering]

Bernhard Voelker wrote:

> On 02/18/2012 02:06 PM, Jim Meyering wrote:
>>> > See the attached getxattr-speedup.log.gz - I added a "cat k.c" so that
>>> > you can check that I got your patch right.
>>> > It seems that GCC doesn't like our "__attribute__((destructor)) void p()".
>>> > It basically works in a standalone program, but not with LD_PRELOAD.
>>> > I didn't find much about this. Can this be a 64-bit issue?
>>
>> Is that an open-suse system?
>> I tried on an opensuse system with 2.6.37.6-0.11-desktop,
>> and since there were no getxattr calls at all, no wrapper
>> would run, and hence, your atexit call would never be reached.
>> I've added this comment at the top:
>
> Yes, it is a OpenSuSE 12.1 with kernel 3.1.9-1.4-desktop.
>
>>   # This test is skipped on systems that lack LD_PRELOAD support; that's 
>> fine.
>
> It doesn't lack LD_PRELOAD support, it simply doesn't call the destructor.

That comment was not intended to describe your case,
but rather any system that lacks LD_PRELOAD support.

>> + # Similarly, on a system that lacks getxattr altogether, skipping it is 
>> fine.
>>
>> and this new skip_ use below:
>>
>> test -f x || skip_ "internal test failure: maybe LD_PRELOAD doesn't work?"
>>
>> Which may mean this test will simply be skipped on your system.
>> But that is fine.
>
> Maybe, but why is LD_PRELOAD honoring the "__attribute__((destructor))",
> and on some systems not?

Good question.
There must be some OpenSuSE 12.1 users willing to investigate.
Filing a bug report should get their attention.

>> +ld -G k.o -lc -o k.so || framework_failure_ 'failed to invoke ld -G ...'
>
> I just added "-lc" for pulling in atexit(). It's not needed in your version.

Thanks.

>From 641143a0cc613a503b80457b3c64dc46c9864980 Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <address@hidden>
Date: Fri, 24 Feb 2012 12:22:20 +0100
Subject: [PATCH] tests: remove unnecessary use of -lc

* tests/ls/getxattr-speedup: Remove unneeded use of -lc.
---
 tests/ls/getxattr-speedup |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ls/getxattr-speedup b/tests/ls/getxattr-speedup
index a35dd69..d32e24a 100755
--- a/tests/ls/getxattr-speedup
+++ b/tests/ls/getxattr-speedup
@@ -48,7 +48,7 @@ EOF

 # Then compile/link it:
 $CC -fPIC -O2 -c k.c || framework_failure_ 'failed to compile with -fPIC'
-ld -G k.o -lc -o k.so || framework_failure_ 'failed to invoke ld -G ...'
+ld -G k.o -o k.so || framework_failure_ 'failed to invoke ld -G ...'

 # Create a few files:
 seq 20 | xargs touch || framework_failure_
--
1.7.9.2.263.g9be8b7