Messages in this thread | | | Subject | Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups | From | Manfred Spraul <> | Date | Sun, 1 Nov 2015 05:32:03 +0100 |
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Hi Sebastian,
On 10/30/2015 12:26 PM, Sebastian Andrzej Siewior wrote: > This patch moves the wakeup_process() invocation so it is not done under > the perm->lock by making use of a lockless wake_q. With this change, the > waiter is woken up once the message has been assigned and it does not > need to loop on SMP if the message points to NULL. In the signal case we > still need to check the pointer under the lock to verify the state. > > This change should also avoid the introduction of preempt_disable() in > -RT which avoids a busy-loop which pools for the NULL -> !NULL > change if the waiter has a higher priority compared to the waker. with regards to functional tests: fakeroot is a heavy system V user (at least if it is configured for sysv). "make -j" under fakeroot was a useful stresstest
with regards to benchmarks: I've attached one of my files.
Otherwise: Nice!
-- Manfred
/* * pmsg.cpp, parallel sysv msg pingpong * * Copyright (C) 1999, 2001, 2005, 2008 by Manfred Spraul. * All rights reserved except the rights granted by the GPL. * * Redistribution of this file is permitted under the terms of the GNU * General Public License (GPL) version 2 or later. * $Header$ */
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <getopt.h> #include <errno.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> #include <pthread.h>
//////////////////////////////////////////////////////////////////////////////
static enum { WAITING, RUNNING, STOPPED, } volatile g_state = WAITING;
unsigned long long *g_results; int g_svmsg_id; pthread_t *g_threads;
struct taskinfo { int svmsg_id; int threadid; int cpuid; int sender; int offset; };
#define DATASIZE 16
void* worker_thread(void *arg) { struct taskinfo *ti = (struct taskinfo*)arg; unsigned long long rounds; int ret; struct { long mtype; unsigned char buffer[DATASIZE]; } mbuf;
{ cpu_set_t cpus; CPU_ZERO(&cpus); CPU_SET(ti->cpuid, &cpus);
ret = pthread_setaffinity_np(g_threads[ti->threadid], sizeof(cpus), &cpus); if (ret < 0) { printf("pthread_setaffinity_np failed for thread %d with errno %d.\n", ti->threadid, errno); }
ret = pthread_getaffinity_np(g_threads[ti->threadid], sizeof(cpus), &cpus); if (ret < 0) { printf("pthread_getaffinity_np() failed for thread %d with errno %d.\n", ti->threadid, errno); fflush(stdout); } else { printf("thread %d: sysvmsg %8d, offset 0x%08x type %d bound to %04lxh\n",ti->threadid, ti->svmsg_id, ti->offset, ti->sender, cpus.__bits[0]); } fflush(stdout); }
rounds = 0; while(g_state == WAITING) { #ifdef __i386__ __asm__ __volatile__("pause": : :"memory"); #endif }
if (ti->sender) { mbuf.mtype = ti->offset+ti->sender+1; mbuf.buffer[0] = ti->offset & 0xff; mbuf.buffer[1] = (ti->offset >> 8) & 0xff; ret = msgsnd(ti->svmsg_id, &mbuf, DATASIZE, 0); if (ret != 0) { printf("Initial send failed, errno %d.\n", errno); exit(1); } } while(g_state == RUNNING) { int target = ti->offset+1+!ti->sender;
ret = msgrcv(ti->svmsg_id, &mbuf, DATASIZE, target, 0); if (ret != DATASIZE) { if (errno == EIDRM) break; printf("Error on msgrcv, got %d, errno %d.\n", ret, errno); exit(1); } if ((mbuf.buffer[0] != (unsigned)(ti->offset & 0xff)) || (mbuf.buffer[1] != (unsigned)((ti->offset >> 8) & 0xff))) { printf("Error - incorrect message received.\n"); printf("cpu %d ti->offset 0x%08x ti->sender %d.\n", ti->cpuid, ti->offset, ti->sender);
printf("got %02x%02x.\n", (unsigned char)mbuf.buffer[0], (unsigned char)mbuf.buffer[1]); exit(1); } mbuf.mtype = ti->offset+ti->sender+1; ret = msgsnd(ti->svmsg_id, &mbuf, DATASIZE, 0); if (ret != 0) { if (errno == EIDRM) break; printf("send failed, errno %d.\n", errno); exit(1); } rounds++; } /* store result */ g_results[ti->threadid] = rounds;
pthread_exit(0); return NULL; }
void init_threads(int cpu, int cpus) { int ret; struct taskinfo *ti1, *ti2;
ti1 = new (struct taskinfo); ti2 = new (struct taskinfo); if (!ti1 || !ti2) { printf("Could not allocate task info\n"); exit(1); }
if (cpu == 0) { g_svmsg_id = msgget(IPC_PRIVATE,0777|IPC_CREAT); if(g_svmsg_id == -1) { printf(" message queue create failed.\n"); exit(1); } }
g_results[cpu] = 0; g_results[cpu+cpus] = 0;
ti1->svmsg_id = g_svmsg_id; ti1->offset = 3*cpu+5; ti1->threadid = cpu; ti1->cpuid = cpu; ti1->sender = 1; ti2->svmsg_id = g_svmsg_id; ti2->offset = ti1->offset; ti2->threadid = cpu+cpus; ti2->cpuid = cpu; ti2->sender = 0;
ret = pthread_create(&g_threads[ti1->threadid], NULL, worker_thread, ti1); if (ret) { printf(" pthread_create failed with error code %d\n", ret); exit(1); } ret = pthread_create(&g_threads[ti2->threadid], NULL, worker_thread, ti2); if (ret) { printf(" pthread_create failed with error code %d\n", ret); exit(1); } }
//////////////////////////////////////////////////////////////////////////////
int main(int argc, char **argv) { int queues, timeout; unsigned long long totals; int i; int res;
printf("pmsg [nr queues] [timeout]\n"); if (argc != 3) { printf(" Invalid parameters.\n"); return 0; } queues = atoi(argv[1]); timeout = atoi(argv[2]); printf("Using %d queues/cpus (%d threads) for %d seconds.\n", queues, 2*queues, timeout);
g_results = new unsigned long long[2*queues]; g_threads = new pthread_t[2*queues]; for (i=0;i<queues;i++) { init_threads(i, queues); }
sleep(1); g_state = RUNNING; sleep(timeout); g_state = STOPPED; sleep(1);
res = msgctl(g_svmsg_id,IPC_RMID,NULL); if (res < 0) { printf("msgctl(IPC_RMID) failed for %d, errno%d.\n", g_svmsg_id, errno); } for (i=0;i<2*queues;i++) pthread_join(g_threads[i], NULL);
printf("Result matrix:\n"); totals = 0; for (i=0;i<queues;i++) { printf(" Thread %3d: %8lld %3d: %8lld\n", i, g_results[i], i+queues, g_results[i+queues]); totals += g_results[i] + g_results[i+queues]; } printf("Total: %lld\n", totals); }
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