Messages in this thread | | | From | Keith Owens <> | Subject | Re: [(resend)patch 3/7] Notify page fault call chain for ia64 | Date | Thu, 20 Apr 2006 12:18:25 +1000 |
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Anil S Keshavamurthy (on Wed, 19 Apr 2006 15:14:22 -0700) wrote: >Overloading of page fault notification with the >notify_die() has performance issues(since the >only interested components for page fault is >kprobes and/or kdb) and hence this patch introduces >the new notifier call chain exclusively for page >fault notifications their by avoiding notifying >unnecessary components in the do_page_fault() code >path. > >Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> > >--- > arch/ia64/kernel/traps.c | 11 +++++++++++ >=================================================================== >--- linux-2.6.17-rc1-mm3.orig/arch/ia64/kernel/traps.c >+++ linux-2.6.17-rc1-mm3/arch/ia64/kernel/traps.c >@@ -31,6 +31,7 @@ fpswa_interface_t *fpswa_interface; > EXPORT_SYMBOL(fpswa_interface); > > ATOMIC_NOTIFIER_HEAD(ia64die_chain); >+ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); > > int > register_die_notifier(struct notifier_block *nb) >@@ -46,6 +47,16 @@ unregister_die_notifier(struct notifier_ > } > EXPORT_SYMBOL_GPL(unregister_die_notifier); > >+int register_page_fault_notifier(struct notifier_block *nb) >+{ >+ return atomic_notifier_chain_register(¬ify_page_fault_chain, nb); >+} >+ >+int unregister_page_fault_notifier(struct notifier_block *nb) >+{ >+ return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); >+} >+
Why is register_page_fault_notifier defined in traps.c? Surely it should be in mm/fault.c, which is the only place that uses the chain.
> trap_init (void) > { >Index: linux-2.6.17-rc1-mm3/arch/ia64/mm/fault.c >=================================================================== >--- linux-2.6.17-rc1-mm3.orig/arch/ia64/mm/fault.c >+++ linux-2.6.17-rc1-mm3/arch/ia64/mm/fault.c >@@ -84,7 +84,7 @@ ia64_do_page_fault (unsigned long addres > /* > * This is to handle the kprobes on user space access instructions > */ >- if (notify_die(DIE_PAGE_FAULT, "page fault", regs, code, TRAP_BRKPT, >+ if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, code, TRAP_BRKPT, > SIGSEGV) == NOTIFY_STOP) > return;
Since this is a critical path, please remove all references to notify_page_fault() and its register functions when CONFIG_KPROBES=n.
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