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author	Venkatesh Pallipadi <venki@google.com>	2010-10-04 20:03:23 -0400
committer	Ingo Molnar <mingo@elte.hu>	2010-10-18 14:52:29 -0400
commit	d267f87fb8179c6dba03d08b91952e81bc3723c7 (patch)
tree	ddcd2f7429964367fcb4ab1dd230a970452d72da /tools/perf/scripts/python
parent	aa483808516ca5cacfa0e5849691f64fec25828e (diff)

sched: Call tick_check_idle before __irq_enter

When CPU is idle and on first interrupt, irq_enter calls tick_check_idle() to notify interruption from idle. But, there is a problem if this call is done after __irq_enter, as all routines in __irq_enter may find stale time due to yet to be done tick_check_idle. Specifically, trace calls in __irq_enter when they use global clock and also account_system_vtime change in this patch as it wants to use sched_clock_cpu() to do proper irq timing. But, tick_check_idle was moved after __irq_enter intentionally to prevent problem of unneeded ksoftirqd wakeups by the commit ee5f80a: irq: call __irq_enter() before calling the tick_idle_check Impact: avoid spurious ksoftirqd wakeups Moving tick_check_idle() before __irq_enter and wrapping it with local_bh_enable/disable would solve both the problems. Fixed-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286237003-12406-9-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Diffstat (limited to 'tools/perf/scripts/python')

0 files changed, 0 insertions, 0 deletions

&read_fifo_fops; pipe->r_counter++; if (pipe->readers++ == 0) wake_up_partner(inode); if (!pipe->writers) { if ((filp->f_flags & O_NONBLOCK)) { /* suppress POLLHUP until we have * seen a writer */ filp->f_version = pipe->w_counter; } else { wait_for_partner(inode, &pipe->w_counter); if(signal_pending(current)) goto err_rd; } } break; case 2: /* * O_WRONLY * POSIX.1 says that O_NONBLOCK means return -1 with * errno=ENXIO when there is no process reading the FIFO. */ ret = -ENXIO; if ((filp->f_flags & O_NONBLOCK) && !pipe->readers) goto err; filp->f_op = &write_fifo_fops; pipe->w_counter++; if (!pipe->writers++) wake_up_partner(inode); if (!pipe->readers) { wait_for_partner(inode, &pipe->r_counter); if (signal_pending(current)) goto err_wr; } break; case 3: /* * O_RDWR * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. * This implementation will NEVER block on a O_RDWR open, since * the process can at least talk to itself. */ filp->f_op = &rdwr_fifo_fops; pipe->readers++; pipe->writers++; pipe->r_counter++; pipe->w_counter++; if (pipe->readers == 1 || pipe->writers == 1) wake_up_partner(inode); break; default: ret = -EINVAL; goto err; } /* Ok! */ mutex_unlock(&inode->i_mutex); return 0; err_rd: if (!--pipe->readers) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err_wr: if (!--pipe->writers) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err: if (!pipe->readers && !pipe->writers) free_pipe_info(inode); err_nocleanup: mutex_unlock(&inode->i_mutex); return ret; } /* * Dummy default file-operations: the only thing this does * is contain the open that then fills in the correct operations * depending on the access mode of the file... */ const struct file_operations def_fifo_fops = { .open = fifo_open, /* will set read or write pipe_fops */ };