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Add an environment variable for controlling the default Thread quantum

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This commit adds an environment variable `RUBY_THREAD_TIMESLICE` for
specifying the default thread quantum in milliseconds.  You can adjust
this variable to tune throughput, which is especially useful on
multithreaded systems that are mixing CPU bound work and IO bound work.

The default quantum remains 100ms.

[Feature #20861]

Co-Authored-By: John Hawthorn <john@hawthorn.email>
This commit is contained in:
Aaron Patterson 2024-11-01 15:06:35 -07:00 committed by Aaron Patterson
parent e7ee7d43f3
commit fffef9aa5d
Notes: git 2024-12-13 00:05:07 +00:00 
Merged: https://github.com/ruby/ruby/pull/11981
4 changed files with 13 additions and 12 deletions
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4
man/ruby.1
View File

@ -537,6 +537,10 @@ Introduced in Ruby 3.3, default: unset.
.Pp
.It Ev RUBY_PAGER
The pager command that will be used for
.Pp
.It Ev RUBY_THREAD_TIMESLICE
Sets the default thread time slice (thread quantum) in milliseconds.
Introduced in Ruby 3.4, default: 100ms.
.Fl -help
option.
Introduced in Ruby 3.0, default:

10
thread.c
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@ -116,6 +116,8 @@ static VALUE sym_immediate;
static VALUE sym_on_blocking;
static VALUE sym_never;
static uint32_t thread_default_quantum_ms = 100;
#define THREAD_LOCAL_STORAGE_INITIALISED FL_USER13
#define THREAD_LOCAL_STORAGE_INITIALISED_P(th) RB_FL_TEST_RAW((th), THREAD_LOCAL_STORAGE_INITIALISED)
@ -2538,7 +2540,7 @@ rb_threadptr_execute_interrupts(rb_thread_t *th, int blocking_timing)
}
if (timer_interrupt) {
uint32_t limits_us = TIME_QUANTUM_USEC;
uint32_t limits_us = thread_default_quantum_ms * 1000;
if (th->priority > 0)
limits_us <<= th->priority;
@ -5506,6 +5508,12 @@ Init_Thread(void)
rb_define_method(cThGroup, "enclosed?", thgroup_enclosed_p, 0);
rb_define_method(cThGroup, "add", thgroup_add, 1);
const char * ptr = getenv("RUBY_THREAD_TIMESLICE");
if (ptr) {
thread_default_quantum_ms = (uint32_t)strtol(ptr, NULL, 0);
}
{
th->thgroup = th->ractor->thgroup_default = rb_obj_alloc(cThGroup);
rb_define_const(cThGroup, "Default", th->thgroup);

4
thread_none.c
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@ -19,10 +19,6 @@
# include "wasm/machine.h"
#endif
#define TIME_QUANTUM_MSEC (100)
#define TIME_QUANTUM_USEC (TIME_QUANTUM_MSEC * 1000)
#define TIME_QUANTUM_NSEC (TIME_QUANTUM_USEC * 1000)
// Do nothing for GVL
static void
thread_sched_to_running(struct rb_thread_sched *sched, rb_thread_t *th)

7
thread_pthread.c
View File

@ -317,13 +317,6 @@ static void threadptr_trap_interrupt(rb_thread_t *);
#define native_thread_yield() ((void)0)
#endif
/* 100ms. 10ms is too small for user level thread scheduling
* on recent Linux (tested on 2.6.35)
*/
#define TIME_QUANTUM_MSEC (100)
#define TIME_QUANTUM_USEC (TIME_QUANTUM_MSEC * 1000)
#define TIME_QUANTUM_NSEC (TIME_QUANTUM_USEC * 1000)
static void native_thread_dedicated_inc(rb_vm_t *vm, rb_ractor_t *cr, struct rb_native_thread *nt);
static void native_thread_dedicated_dec(rb_vm_t *vm, rb_ractor_t *cr, struct rb_native_thread *nt);
static void native_thread_assign(struct rb_native_thread *nt, rb_thread_t *th);