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path: root/arch/sparc64/kernel/smp.c
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2005-11-11[SPARC64]: Restore 2.4.x /proc/cpuinfo behavior for "ncpus probed" field.David S. Miller
Noticed by Tom 'spot' Callaway. Even on uniprocessor we always reported the number of physical cpus in the system via /proc/cpuinfo. But when this got changed to use num_possible_cpus() it always reads as "1" on uniprocessor. This change was unintentional. So scan the firmware device tree and count the number of cpu nodes, and report that, as we always did. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-09[PATCH] sched: resched and cpu_idle reworkNick Piggin
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce confusion, and make their semantics rigid. Improves efficiency of resched_task and some cpu_idle routines. * In resched_task: - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held, and as we hold it during resched_task, then there is no need for an atomic test and set there. The only other time this should be set is when the task's quantum expires, in the timer interrupt - this is protected against because the rq lock is irq-safe. - If TIF_NEED_RESCHED is set, then we don't need to do anything. It won't get unset until the task get's schedule()d off. - If we are running on the same CPU as the task we resched, then set TIF_NEED_RESCHED and no further action is required. - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set after TIF_NEED_RESCHED has been set, then we need to send an IPI. Using these rules, we are able to remove the test and set operation in resched_task, and make clear the previously vague semantics of POLLING_NRFLAG. * In idle routines: - Enter cpu_idle with preempt disabled. When the need_resched() condition becomes true, explicitly call schedule(). This makes things a bit clearer (IMO), but haven't updated all architectures yet. - Many do a test and clear of TIF_NEED_RESCHED for some reason. According to the resched_task rules, this isn't needed (and actually breaks the assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock held). So remove that. Generally one less locked memory op when switching to the idle thread. - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner most polling idle loops. The above resched_task semantics allow it to be set until before the last time need_resched() is checked before going into a halt requiring interrupt wakeup. Many idle routines simply never enter such a halt, and so POLLING_NRFLAG can be always left set, completely eliminating resched IPIs when rescheduling the idle task. POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09[PATCH] sched: disable preempt in idle tasksNick Piggin
Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07[SPARC64] mm: Do not flush TLB mm in tlb_finish_mmu()David S. Miller
It isn't needed any longer, as noted by Hugh Dickins. We still need the flush routines, due to the one remaining call site in hugetlb_prefault_arch_hook(). That can be eliminated at some later point, however. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-07[SPARC64] mm: context switch ptlockHugh Dickins
sparc64 is unique among architectures in taking the page_table_lock in its context switch (well, cris does too, but erroneously, and it's not yet SMP anyway). This seems to be a private affair between switch_mm and activate_mm, using page_table_lock as a per-mm lock, without any relation to its uses elsewhere. That's fine, but comment it as such; and unlock sooner in switch_mm, more like in activate_mm (preemption is disabled here). There is a block of "if (0)"ed code in smp_flush_tlb_pending which would have liked to rely on the page_table_lock, in switch_mm and elsewhere; but its comment explains how dup_mmap's flush_tlb_mm defeated it. And though that could have been changed at any time over the past few years, now the chance vanishes as we push the page_table_lock downwards, and perhaps split it per page table page. Just delete that block of code. Which leaves the mysterious spin_unlock_wait(&oldmm->page_table_lock) in kernel/fork.c copy_mm. Textual analysis (supported by Nick Piggin) suggests that the comment was written by DaveM, and that it relates to the defeated approach in the sparc64 smp_flush_tlb_pending. Just delete this block too. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-10-14[SPARC64]: Fix powering off on SMP.David S. Miller
Doing a "SUNW,stop-self" firmware call on the other cpus is not the correct thing to do when dropping into the firmware for a halt, reboot, or power-off. For now, just do nothing to quiet the other cpus, as the system should be quiescent enough. Later we may decide to implement smp_send_stop() like the other SMP platforms do. Based upon a report from Christopher Zimmermann. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-26[SPARC64]: Probe D/I/E-cache config and use.David S. Miller
At boot time, determine the D-cache, I-cache and E-cache size and line-size. Use them in cache flushes when appropriate. This change was motivated by discovering that the D-cache on UltraSparc-IIIi and later are 64K not 32K, and the flushes done by the Cheetah error handlers were assuming a 32K size. There are still some pieces of code that are hard coding things and will need to be fixed up at some point. While we're here, fix the D-cache and I-cache parity error handlers to run with interrupts disabled, and when the trap occurs at trap level > 1 log the event via a counter displayed in /proc/cpuinfo. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29[SPARC64]: More fully work around Spitfire Errata 51.David S. Miller
It appears that a memory barrier soon after a mispredicted branch, not just in the delay slot, can cause the hang condition of this cpu errata. So move them out-of-line, and explicitly put them into a "branch always, predict taken" delay slot which should fully kill this problem. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-24[SPARC64]: Move syscall success and newchild state out of thread flags.David S. Miller
These two bits were accesses non-atomically from assembler code. So, in order to eliminate any potential races resulting from that, move these pieces of state into two bytes elsewhere in struct thread_info. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-12[SPARC64]: Fix SMP build failure.Andrew Morton
arch/sparc64/kernel/smp.c:48: error: parse error before "__attribute__" arch/sparc64/kernel/smp.c:49: error: parse error before "__attribute__" Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-10[SPARC64]: Add __read_mostly support.David S. Miller
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-23[SPARC64]: Add boot option to force UltraSPARC-III P-Cache on.David S. Miller
Older UltraSPARC-III chips have a P-Cache bug that makes us disable it by default at boot time. However, this does hurt performance substantially, particularly with memcpy(), and the bug is _incredibly_ obscure. I have never seen it triggered in practice, ever. So provide a "-P" boot option that forces the P-Cache on. It taints the kernel, so if it does trigger and cause some data corruption or OOPS, we will find out in the logs that this option was on when it happened. Signed-off-by: David S. Miller <davem@davemloft.net>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!