[PATCH] Makefile: add NO_CLOCK_GETTIME check

[PATCH] Makefile: add NO_CLOCK_GETTIME check

[Reuben Hawkins]

Some really old platforms, rhel3, which don't define CLOCK_MONOTONIC, still
need a way to build git.  Some high resolution timer code was added Jul 12,
2014 to aid debugging performance issues.  That code uses clock_gettime and
CLOCK_MONOTONIC.  That change breaks building git on ancient platforms which
don't support CLOCK_MONOTONIC, so a way to disable that code is needed.

To use this feature...

$ make NO_CLOCK_GETTIME=1

This change amends the commit...

 commit 148d6771bf5e00aa1d7fa2221507a3dfe4c1e37f
 Author: Karsten Blees <karsten.blees@gmail.com>
 Date:   Sat Jul 12 02:05:42 2014 +0200

  trace: add high resolution timer function to debug performance issues
---
 Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Makefile b/Makefile
index 9f984a9..0c1c8cf 100644
--- a/Makefile
+++ b/Makefile
@@ -1502,10 +1502,12 @@ ifdef GMTIME_UNRELIABLE_ERRORS
 	BASIC_CFLAGS += -DGMTIME_UNRELIABLE_ERRORS
 endif
 
+ifndef NO_CLOCK_GETTIME
 ifdef HAVE_CLOCK_GETTIME
 	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
 	EXTLIBS += -lrt
 endif
+endif
 
 ifeq ($(TCLTK_PATH),)
 NO_TCLTK = NoThanks
-- 
1.9.1

Re: [PATCH] Makefile: add NO_CLOCK_GETTIME check

[Junio C Hamano]

Reuben Hawkins <reubenhwk@gmail.com> writes:

> Some really old platforms, rhel3, which don't define CLOCK_MONOTONIC, still
> need a way to build git.  Some high resolution timer code was added Jul 12,
> 2014 to aid debugging performance issues.  That code uses clock_gettime and
> CLOCK_MONOTONIC.  That change breaks building git on ancient platforms which
> don't support CLOCK_MONOTONIC, so a way to disable that code is needed.
>
> To use this feature...
>
> $ make NO_CLOCK_GETTIME=1
>
> This change amends the commit...
>
>  commit 148d6771bf5e00aa1d7fa2221507a3dfe4c1e37f
>  Author: Karsten Blees <karsten.blees@gmail.com>
>  Date:   Sat Jul 12 02:05:42 2014 +0200
>
>   trace: add high resolution timer function to debug performance issues
> ---

>  Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 9f984a9..0c1c8cf 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1502,10 +1502,12 @@ ifdef GMTIME_UNRELIABLE_ERRORS
>  	BASIC_CFLAGS += -DGMTIME_UNRELIABLE_ERRORS
>  endif
>  
> +ifndef NO_CLOCK_GETTIME
>  ifdef HAVE_CLOCK_GETTIME
>  	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
>  	EXTLIBS += -lrt
>  endif
> +endif

I am not sure why you even need this change.  Wouldn't you get
exactly the same result if you did not define HAVE_CLOCK_GETTIME
when building?



>  
>  ifeq ($(TCLTK_PATH),)
>  NO_TCLTK = NoThanks

Re: [PATCH] Makefile: add NO_CLOCK_GETTIME check

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

>> +ifndef NO_CLOCK_GETTIME
>>  ifdef HAVE_CLOCK_GETTIME
>>  	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
>>  	EXTLIBS += -lrt
>>  endif
>> +endif
>
> I am not sure why you even need this change.  Wouldn't you get
> exactly the same result if you did not define HAVE_CLOCK_GETTIME
> when building?

That is, doing something like:

    $ make HAVE_CLOCK_GETTIME= V=1

would show lines like:

    cc -o credential-store.o -c -MF ./.depend/credential-store.o.d
    -MQ credential-store.o -MMD -MP  -O2 -Wall -Wvla
    -Wdeclaration-after-statement -Wno-format-zero-length -g
    -I. -DHAVE_ALLOCA_H  -DHAVE_PATHS_H -DHAVE_DEV_TTY
    -DXDL_FAST_HASH -DSHA1_HEADER='"block-sha1/sha1.h"'
    -DNO_STRLCPY -DNO_MKSTEMPS -DSHELL_PATH='"/bin/sh"'  credential-store.c

that does not have -DHAVE_CLOCK_GETTIME on the command line, no?