From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Wed, 25 Jan 2006 09:04:01 +0000 Subject: RE: [PATCH] SN2 user-MMIO CPU migration Message-Id: <200601250904.k0P941g22471@unix-os.sc.intel.com> List-Id: References: <20060118163305.Y42462@chenjesu.americas.sgi.com> In-Reply-To: <20060118163305.Y42462@chenjesu.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Brent Casavant wrote on Tuesday, January 24, 2006 4:11 PM > > Brent Casavant wrote on Tuesday, January 24, 2006 3:29 PM > > > Take 4. Moved "really migrated?" check as late as possible in > > > __switch_task(), and moved thread_info last_cpu field closer to > > > flags and cpu fields. Some nomenclature changes as well. > > > > I think you should seriously consider my other proposal :-) > > Well... if Ingo is amenable to the arch hook in the scheduler, I'm > OK with changing directions. Again. :-) Hmm, I'm not proposing for arch hook at all. > The arch hook would be a lot simpler this time -- simply setting > a flag instead of performing the PIO write drain. Not sure if > that's enough to argue in favor of the hook or not. > > Truth be told, I have no strong preference either way. I'd just > like to break out of this Brownian motion. :-) This is the "what the heck is he talking about?" patch, on top of "take 4" patch: --- Optimize platform_migrate(): call platform specific vector only if machine requires it. Signed-off-by: Ken Chen --- linus-2.6.git/include/asm-ia64/processor.h.orig 2006-01-21 10:58:06.000000000 -0800 +++ linus-2.6.git/include/asm-ia64/processor.h 2006-01-25 01:09:34.169421315 -0800 @@ -50,7 +50,7 @@ #define IA64_THREAD_PM_VALID (__IA64_UL(1) << 2) /* performance registers valid? */ #define IA64_THREAD_UAC_NOPRINT (__IA64_UL(1) << 3) /* don't log unaligned accesses */ #define IA64_THREAD_UAC_SIGBUS (__IA64_UL(1) << 4) /* generate SIGBUS on unaligned acc. */ - /* bit 5 is currently unused */ +#define IA64_THREAD_MIGRATION (__IA64_UL(1) << 5) /* require migration sync at ctx sw */ #define IA64_THREAD_FPEMU_NOPRINT (__IA64_UL(1) << 6) /* don't log any fpswa faults */ #define IA64_THREAD_FPEMU_SIGFPE (__IA64_UL(1) << 7) /* send a SIGFPE for fpswa faults */ --- linus-2.6.git/include/asm-ia64/system.h.orig 2006-01-25 01:14:07.661605464 -0800 +++ linus-2.6.git/include/asm-ia64/system.h 2006-01-25 01:17:36.173321660 -0800 @@ -221,23 +221,12 @@ extern void ia64_load_extra (struct task ((t)->thread.flags & (IA64_THREAD_DBG_VALID|IA64_THREAD_PM_VALID) \ || IS_IA32_PROCESS(task_pt_regs(t)) || PERFMON_IS_SYSWIDE()) -#ifdef CONFIG_SMP -# define arch_migrate(task) \ - if (task_cpu(task) != task_thread_info(task)->last_cpu) { \ - platform_migrate(task); \ - task_thread_info(task)->last_cpu = task_cpu(task); \ - } -#else -# define arch_migrate(task) do { } while(0) -#endif - #define __switch_to(prev,next,last) do { \ if (IA64_HAS_EXTRA_STATE(prev)) \ ia64_save_extra(prev); \ if (IA64_HAS_EXTRA_STATE(next)) \ ia64_load_extra(next); \ ia64_psr(task_pt_regs(next))->dfh = !ia64_is_local_fpu_owner(next); \ - arch_migrate(next); \ (last) = ia64_switch_to((next)); \ } while (0) @@ -255,6 +244,8 @@ extern void ia64_load_extra (struct task __ia64_save_fpu((prev)->thread.fph); \ } \ __switch_to(prev, next, last); \ + if (unlikely((next)->thread.flags & IA64_THREAD_MIGRATION)) \ + platform_migrate(next); \ } while (0) #else # define switch_to(prev,next,last) __switch_to(prev, next, last) --- linus-2.6.git/arch/ia64/sn/kernel/sn2/sn2_smp.c.orig 2006-01-25 01:13:56.322738416 -0800 +++ linus-2.6.git/arch/ia64/sn/kernel/sn2/sn2_smp.c 2006-01-25 01:19:27.169414050 -0800 @@ -184,9 +184,13 @@ void sn_migrate(struct task_struct *task volatile unsigned long *adr = last_pda->pio_write_status_addr; unsigned long val = last_pda->pio_write_status_val; + if (task_cpu(task) = task_thread_info(task)->last_cpu) + return; + /* Drain PIO writes from old CPU's Shub */ while ((*adr & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK) != val) cpu_relax(); + task_thread_info(task)->last_cpu = task_cpu(task); } void sn_tlb_migrate_finish(struct mm_struct *mm) --- linus-2.6.git/arch/ia64/sn/kernel/setup.c.orig 2006-01-25 01:02:30.830559313 -0800 +++ linus-2.6.git/arch/ia64/sn/kernel/setup.c 2006-01-25 01:09:57.794421025 -0800 @@ -496,6 +496,7 @@ void __init sn_setup(char **cmdline_p) * for sn. */ pm_power_off = ia64_sn_power_down; + current->thread.flags |= IA64_THREAD_MIGRATION; } /**