staging: lustre: replace direct LNet HZ access with kernel APIs
authorJian Yu <jian.yu@intel.com>
Wed, 2 Mar 2016 22:01:53 +0000 (17:01 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 2 Mar 2016 23:23:49 +0000 (15:23 -0800)
commit27d81ace4f93b51db839bd8b21b4a6039b182387
treef37c75c017c7b276fc2434fd3455911990227f6d
parent933d36ba1485abe4f3d7ae23cecf87a2b71020d1
staging: lustre: replace direct LNet HZ access with kernel APIs

On some customers' systems, the kernel was compiled with HZ defined
to 100, instead of 1000. This improves performance for HPC applications.
However, to use these systems with Lustre, customers have to re-build
Lustre for the kernel because Lustre directly uses the defined constant
HZ.

Since kernel 2.6.21, some non-HZ dependent timing APIs become non-
inline functions, which can be used in Lustre codes to replace the
direct HZ access.

These kernel APIs include:
 jiffies_to_msecs()
 jiffies_to_usecs()
 jiffies_to_timespec()
 msecs_to_jiffies()
 usecs_to_jiffies()
 timespec_to_jiffies()

And here are some samples of the replacement:
 HZ            -> msecs_to_jiffies(MSEC_PER_SEC)
 n * HZ        -> msecs_to_jiffies(n * MSEC_PER_SEC)
 HZ / n        -> msecs_to_jiffies(MSEC_PER_SEC / n)
 n / HZ        -> jiffies_to_msecs(n) / MSEC_PER_SEC
 n / HZ * 1000 -> jiffies_to_msecs(n)

This patch replaces the direct HZ access in lnet module.

Signed-off-by: Jian Yu <jian.yu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5443
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd.h
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
drivers/staging/lustre/lnet/lnet/api-ni.c
drivers/staging/lustre/lnet/lnet/lib-socket.c
drivers/staging/lustre/lnet/selftest/conrpc.c