Re: apr_atomic functions usage

[Ben Reser]

On Mon, May 27, 2013 at 8:42 PM, kalyan sita  wrote:
> I see that the below functions have specific assembly implementations for
> os32,ia32 architectures:
>
> apr_atomic_add32
> apr_atomic_sub32
> apr_atomic_inc32
> apr_atomic_dec32
> apr_atomic_set32
> apr_atomic_cas32
> apr_atomic_casptr
> apr_atomic_xchg32
> apr_atomic_xchgptr
>
> How frequently are these functions used.
> I am planning to write arm specific code for the above functions in arm.c
> file.
> Can anyone help me where to start ?

You really should direct this at the d...@apr.apache.org list since
it's not part of httpd (granted there's a lot of overlap between the
projects).

These are only used if the compiler doesn't provide the atomic builtins:
http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/_005f_005fsync-Builtins.html#_005f_005fsync-Builtins

If HAVE_ATOMIC_BUILTINS is true in include/arch/unix/apr_private.h
then you don't need the ASM versions.

One of the Linux Kernel hackers (Jon Masters) has a blog post up about
ARM atomic operations:
http://www.jonmasters.org/blog/2012/11/13/arm-atomic-operations/

profiling an apache httpd -X process

[kalyan sita]

Hi all,

 I am able to debug the httpd -X process using eclipse gdb debugger
But I am not able to profile the same.
I am able to profile only a command line application .
Can anyone pl help me out in profile the application with httpd -X process.

Thanks,
kalyan

apr_atomic functions usage

[kalyan sita]

I see that the below functions have specific assembly implementations for
os32,ia32 architectures:

apr_atomic_add32
apr_atomic_sub32
apr_atomic_inc32
apr_atomic_dec32
apr_atomic_set32
apr_atomic_cas32
apr_atomic_casptr
apr_atomic_xchg32
apr_atomic_xchgptr

How frequently are these functions used.
I am planning to write arm specific code for the above functions in arm.c
file.
Can anyone help me where to start ?

Thanks,
Kalyan

[PATCH] Make error logging modular

[Jan Kaluža]

Hi,

last week I was trying to write my own module to log error_log to 
systemd-journal [1] and I've found out that with the current error_log 
code, it's not possible to do that properly.


I was able to use "error_log" hook, but there is no way to disable 
creation of "ErrorLog" file (One can set it to "/dev/null", but httpd 
will still write data to it without any reason). Syslog logger fixes 
that by hardcoding syslog methods in log.c/core.c, but I don't think 
that's the right thing to do with journald.


Therefore, I've created following patches:
http://people.apache.org/~jkaluza/patches/logging/

Their descriptions should be clear from their names, but I will describe 
them briefly here too.


Patch 0001 declares ap_errorlog_provider which can be implemented by 
module providing error_log logger. Admin can later define "ErrorLog 
provider arg" to choose particular errorlog provider. Old syntax still 
works and the change is backward compatible. This patch also removes 
syslog logging from log.c (it is moved to newly created mod_syslog.c in 
next patch)


Patch 0002 creates mod_syslog.c which uses the new API to implement 
syslog logging. It works the same way as the version in log.c I removed 
in previous patch, but it's in separate module.


Patch 0003 shows how mod_journald.c can use the existing API. This 
module works well with systemd-journal, but unfortunately the 
performance of systemd-journal daemon is poor so far [2], but I presume 
it will be fixed and the module will be usable for general use in the 
future. There is probably no real benefit in accepting this last patch 
right now. It's here to only show why the previous two patches are useful.


Note that this is my first bigger patch touching httpd core, so feel 
free to correct my possible mistakes... :)


[1] http://0pointer.de/blog/projects/journalctl.html
[2] https://bugzilla.redhat.com/show_bug.cgi?id=963620
[patches] http://people.apache.org/~jkaluza/patches/logging/

Regards,
Jan Kaluza