[src/trunk]: src/lib/libpthread - A bit more alignment in __pthread_st especi...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ae8e770a86e1
branches:  trunk
changeset: 1006813:ae8e770a86e1
user:      ad <ad%NetBSD.org@localhost>
date:      Tue Jan 28 13:08:40 2020 +0000

description:
- A bit more alignment in __pthread_st especially for the rbtree node.
- Use COHERENCY_UNIT from sys/param.h.

diffstat:

 lib/libpthread/pthread_int.h |  23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)

diffs (66 lines):

diff -r 2956d47a8e01 -r ae8e770a86e1 lib/libpthread/pthread_int.h
--- a/lib/libpthread/pthread_int.h      Tue Jan 28 12:02:02 2020 +0000
+++ b/lib/libpthread/pthread_int.h      Tue Jan 28 13:08:40 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pthread_int.h,v 1.99 2020/01/27 20:50:05 ad Exp $      */
+/*     $NetBSD: pthread_int.h,v 1.100 2020/01/28 13:08:40 ad Exp $     */
 
 /*-
  * Copyright (c) 2001, 2002, 2003, 2006, 2007, 2008, 2020
@@ -47,6 +47,7 @@
 
 #include <sys/atomic.h>
 #include <sys/rbtree.h>
+#include <sys/param.h>
 
 #include <limits.h>
 #include <lwp.h>
@@ -96,7 +97,6 @@
 #endif
        unsigned int    pt_magic;       /* Magic number */
        int             pt_state;       /* running, blocked, etc. */
-       pthread_mutex_t pt_lock;        /* lock on state */
        int             pt_flags;       /* see PT_FLAG_* below */
        int             pt_cancel;      /* Deferred cancellation */
        int             pt_errno;       /* Thread-specific errno. */
@@ -120,15 +120,25 @@
 
        /* LWP ID and entry on the list of all threads. */
        lwpid_t         pt_lid;
-       rb_node_t       pt_alltree;
+       PTQ_ENTRY(__pthread_st) pt_deadq;
+
+       /*
+        * rbtree node and entry on the list of all threads.  pt_alltree in
+        * its own cacheline, so pthread__find() is not needlessly impacted
+        * by threads going about their normal business.  pt_allq is
+        * adjusted at the same time as pt_alltree.
+        */
+       rb_node_t       pt_alltree __aligned(COHERENCY_UNIT);
        PTQ_ENTRY(__pthread_st) pt_allq;
-       PTQ_ENTRY(__pthread_st) pt_deadq;
+
+       /* Lock on state also gets its own line. */
+       pthread_mutex_t pt_lock __aligned(COHERENCY_UNIT);
 
        /*
         * General synchronization data.  We try to align, as threads
         * on other CPUs will access this data frequently.
         */
-       int             pt_dummy1 __aligned(128);
+       int             pt_dummy1 __aligned(COHERENCY_UNIT);
        struct lwpctl   *pt_lwpctl;     /* Kernel/user comms area */
        volatile int    pt_rwlocked;    /* Handed rwlock successfully */
        volatile int    pt_signalled;   /* Received pthread_cond_signal() */
@@ -137,10 +147,9 @@
        void * volatile pt_sleepobj;    /* Object slept on */
        PTQ_ENTRY(__pthread_st) pt_sleep;
        void            (*pt_early)(void *);
-       int             pt_dummy2 __aligned(128);
 
        /* Thread-specific data.  Large so it sits close to the end. */
-       int             pt_havespecific;
+       int             pt_havespecific __aligned(COHERENCY_UNIT);
        struct pt_specific {
                void *pts_value;
                PTQ_ENTRY(pt_specific) pts_next;