linux-kernel - [PATCH] Introduce time_data, a new structure to hold jiffies, xtime, xtime_lock, wall_to_monotonic, calc_load

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Message-id: <200612132226.26535.dada1@cosmosbay.com>
Date:	Wed, 13 Dec 2006 22:26:26 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Andi Kleen <ak@...e.de>, linux-kernel@...r.kernel.org
Subject: [PATCH] Introduce time_data, a new structure to hold jiffies, xtime,
 xtime_lock, wall_to_monotonic, calc_load_count and avenrun

This patch introduces a new structure called time_data, where some time 
keeping related variables are put together to share as few cache lines as 
possible. This should reduce timer interrupt latency and cache lines ping 
pongs in SMP machines.

struct time_data {
        u64                    _jiffies_64;
        struct timespec _xtime;
        struct timespec _wall_to_monotonic;
        seqlock_t           lock;
        int                     calc_load_count;
        unsigned int     _avenrun[3];
};

_jiffies_64 is a place holder so that arches can (optionally) aliases 
jiffies_64/jiffies in time_data. This patch does the thing for i386 and 
x86_64. 

avenrun, xtime, xtime_lock, wall_to_monotonic, are now temporary defined as 
macros to make this patch not too invasive, but we can in future patches 
gradually deletes these macros.

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
---
 arch/i386/kernel/vmlinux.lds.S   |    3 +
 arch/s390/appldata/appldata_os.c |   18 ++++-----
 arch/x86_64/kernel/time.c        |    8 +++-
 arch/x86_64/kernel/vmlinux.lds.S |   14 ++-----
 arch/x86_64/kernel/vsyscall.c    |   15 +++-----
 include/asm-x86_64/vsyscall.h    |    8 +---
 include/linux/jiffies.h          |    2 -
 include/linux/sched.h            |   10 +++--
 include/linux/time.h             |   33 +++++++++++++++--
 kernel/timer.c                   |   54 ++++++++++++++---------------
 10 files changed, 92 insertions(+), 73 deletions(-)

View attachment "time_data.patch" of type "text/plain" (14109 bytes)