- 26 Jul, 2008 40 commits
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Roland McGrath authored
This adds the generic HAVE_ARCH_TRACEHOOK kconfig item. Each arch should add to some Kconfig file: select HAVE_ARCH_TRACEHOOK if the arch code uses all the latest hooks to enable newfangled tracing and debugging code. The comment in arch/Kconfig lists all the prerequisite arch support. When all these are available, setting HAVE_ARCH_TRACEHOOK will allow enabling any new features that depend on the modern arch interfaces. Signed-off-by:
Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by:
Ingo Molnar <mingo@elte.hu> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Roland McGrath authored
This adds asm-generic/syscall.h, which documents what a real asm-ARCH/syscall.h file should define. This is not used yet, but will provide all the machine-dependent details of examining a user system call about to begin, in progress, or just ended. Each arch should add an asm-ARCH/syscall.h that defines all the entry points documented in asm-generic/syscall.h, as short inlines if possible. This lets us write new tracing code that understands user system call registers, without any new arch-specific work. Signed-off-by:
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Roland McGrath authored
This adds tracehook.h inlines to enable a new arch feature in support of user debugging/tracing. This is not used yet, but it lays the groundwork for a debugger to be able to wrangle a task that's possibly running, without interrupting its syscalls in progress. Each arch should define TIF_NOTIFY_RESUME, and in their entry.S code treat it much like TIF_SIGPENDING. That is, it causes you to take the slow path when returning to user mode, where you get the full user-mode state accessible as for signal handling or ptrace. The arch code should check TIF_NOTIFY_RESUME after handling TIF_SIGPENDING. When it's set, clear it and then call tracehook_notify_resume(). In future, tracing code will call set_notify_resume() when it wants to get a callback in tracehook_notify_resume(). Signed-off-by:
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Roland McGrath authored
This defines a new hook tracehook_force_sigpending() that lets tracing code decide to force TIF_SIGPENDING on in recalc_sigpending(). This is not used yet, so it compiles away to nothing for now. It lays the groundwork for new tracing code that can interrupt a task synthetically without actually sending a signal. Signed-off-by:
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Roland McGrath authored
This moves the ptrace logic in task death (exit_notify) into tracehook.h inlines. Some code is rearranged slightly to make things nicer. There is no change, only cleanup. There is one hook called with the tasklist_lock write-locked, as ptrace needs. There is also a new hook called after exit_state changes and without locks. This is a better place for tracing work to be in the future, since it doesn't delay the whole system with locking. Signed-off-by:
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Roland McGrath authored
This defines the tracehook_notify_jctl() hook to formalize the ptrace effects on the job control notifications. There is no change, only cleanup. Signed-off-by:
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Roland McGrath authored
This defines the tracehook_get_signal() hook to allow tracing code to slip in before normal signal dequeuing. This lays the groundwork for new tracing features that can inject synthetic signals outside the normal queue or control the disposition of delivered signals. The calling convention lets tracehook_get_signal() decide both exactly what will happen and what signal number to report in the handler/exit. Signed-off-by:
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Roland McGrath authored
This adds standard tracehook.h inlines for arch code to call when TIF_SYSCALL_TRACE has been set. This replaces having each arch implement the ptrace guts for its syscall tracing support. Signed-off-by:
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Roland McGrath authored
This defines tracehook_consider_fatal_signal() has a fine-grained hook for deciding to skip the special cases for a fatal signal, as ptrace does. There is no change, only cleanup. Signed-off-by:
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Roland McGrath authored
This defines tracehook_consider_ignored_signal() has a fine-grained hook for deciding to prevent the normal short-circuit of sending an ignored signal, as ptrace does. There is no change, only cleanup. Signed-off-by:
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Roland McGrath authored
This defines tracehook_signal_handler() as a hook for the arch signal handling code to call. It gives ptrace the opportunity to stop for a pseudo-single-step trap immediately after signal handler setup is done. Signed-off-by:
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Roland McGrath authored
This adds tracehook_expect_breakpoints() as a formal hook for the nommu code to use for its, "Is text-poking likely?" check at mmap time. This names the actual semantics the code means to test, and documents it. Signed-off-by:
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Roland McGrath authored
This adds the tracehook_tracer_task() hook to consolidate all forms of "Who is using ptrace on me?" logic. This is used for "TracerPid:" in /proc and for permission checks. We also clean up the selinux code the called an identical accessor. Signed-off-by:
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Roland McGrath authored
This moves the ptrace-related logic from release_task into tracehook.h and ptrace.h inlines. It provides clean hooks both before and after locking tasklist_lock, for future tracing logic to do more cleanup without the lock. This also changes release_task() itself in the rare "zap_leader" case to set the leader to EXIT_DEAD before iterating. This maintains the invariant that release_task() only ever handles a task in EXIT_DEAD. This is a common-sense invariant that is already always true except in this one arcane case of zombie leader whose parent ignores SIGCHLD. This change is harmless and only costs one store in this one rare case. It keeps the expected state more consisently sane, which is nicer when debugging weirdness in release_task(). It also lets some future code in the tracehook entry points rely on this invariant for bookkeeping. Signed-off-by:
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Roland McGrath authored
This moves the PTRACE_EVENT_VFORK_DONE tracing into a tracehook.h inline, tracehook_report_vfork_done(). The change has no effect, just clean-up. Signed-off-by:
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Roland McGrath authored
This moves all the ptrace initialization and tracing logic for task creation into tracehook.h and ptrace.h inlines. It reorganizes the code slightly, but should not change any behavior. There are four tracehook entry points, at each important stage of task creation. This keeps the interface from the core fork.c code fairly clean, while supporting the complex setup required for ptrace or something like it. Signed-off-by:
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Roland McGrath authored
This moves the PTRACE_EVENT_EXIT tracing into a tracehook.h inline, tracehook_report_exec(). The change has no effect, just clean-up. Signed-off-by:
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Roland McGrath authored
The ptrace_notify() function should not be called by any modules. It was only ever exported to be called by binfmt exec functions. But that is no longer necessary since fs/exec.c deals with that generically now. There should be no calls to ptrace_notify() from outside the core kernel. Signed-off-by:
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Roland McGrath authored
This moves all the ptrace hooks related to exec into tracehook.h inlines. This also lifts the calls for tracing out of the binfmt load_binary hooks into search_binary_handler() after it calls into the binfmt module. This change has no effect, since all the binfmt modules' load_binary functions did the call at the end on success, and now search_binary_handler() does it immediately after return if successful. We consolidate the repeated code, and binfmt modules no longer need to import ptrace_notify(). Signed-off-by:
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Roland McGrath authored
This patch series introduces the "tracehook" interface layer of inlines in <linux/tracehook.h>. There are more details in the log entry for patch 01/23 and in the header file comments inside that patch. Most of these changes move code around with little or no change, and they should not break anything or change any behavior. This sets a new standard for uniform arch support to enable clean arch-independent implementations of new debugging and tracing stuff, denoted by CONFIG_HAVE_ARCH_TRACEHOOK. Patch 20/23 adds that symbol to arch/Kconfig, with comments listing everything an arch has to do before setting "select HAVE_ARCH_TRACEHOOK". These are elaborted a bit at: http://sourceware.org/systemtap/wiki/utrace/arch/HowTo The new inlines that arch code must define or call have detailed kerneldoc comments in the generic header files that say what is required. No arch is obligated to do any work, and no arch's build should be broken by these changes. There are several steps that each arch should take so it can set HAVE_ARCH_TRACEHOOK. Most of these are simple. Providing this support will let new things people add for doing debugging and tracing of user-level threads "just work" for your arch in the future. For an arch that does not provide HAVE_ARCH_TRACEHOOK, some new options for such features will not be available for config. I have done some arch work and will submit this to the arch maintainers after the generic tracehook series settles in. For now, that work is available in my GIT repositories, and in patch and mbox-of-patches form at http://people.redhat.com/roland/utrace/2.6-current/ This paves the way for my "utrace" work, to be submitted later. But it is not innately tied to that. I hope that the tracehook series can go in soon regardless of what eventually does or doesn't go on top of it. For anyone implementing any kind of new tracing/debugging plan, or just understanding all the context of the existing ptrace implementation, having tracehook.h makes things much easier to find and understand. This patch: This adds the new kernel-internal header file <linux/tracehook.h>. This is not yet used at all. The comments in the header introduce what the following series of patches is about. The aim is to formalize and consolidate all the places that the core kernel code and the arch code now ties into the ptrace implementation. These patches mostly don't cause any functional change. They just move the details of ptrace logic out of core code into tracehook.h inlines, where they are mostly compiled away to the same as before. All that changes is that everything is thoroughly documented and any future reworking of ptrace, or addition of something new, would not have to touch core code all over, just change the tracehook.h inlines. The new linux/ptrace.h inlines are used by the following patches in the new tracehook_*() inlines. Using these helpers for the ptrace event stops makes it simple to change or disable the old ptrace implementation of these stops conditionally later. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. This way, the entire if() {} section can collapse into the WARN() as well. Signed-off-by:Arjan van de Ven <arjan@linux.intel.com> Acked-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Also, with this, one fo the if() sections collapses entirely into the WARN(). Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. In addition, one of the if() clauses collapes into the WARN() entirely now. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by:
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Arjan van de Ven authored
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by:
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Arjan van de Ven authored
Replace a printk+WARN_ON() by a WARN(); this increases the chance of the string making it into the bugreport (ie: it goes inside the ---[ cut here ]--- section) Signed-off-by:
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Alexey Dobriyan authored
Kmem cache passed to constructor is only needed for constructors that are themselves multiplexeres. Nobody uses this "feature", nor does anybody uses passed kmem cache in non-trivial way, so pass only pointer to object. Non-trivial places are: arch/powerpc/mm/init_64.c arch/powerpc/mm/hugetlbpage.c This is flag day, yes. Signed-off-by:
Pekka Enberg <penberg@cs.helsinki.fi> Acked-by:
Christoph Lameter <cl@linux-foundation.org> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Matt Mackall <mpm@selenic.com> [akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c] [akpm@linux-foundation.org: fix mm/slab.c] [akpm@linux-foundation.org: fix ubifs] Signed-off-by:
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Matt LaPlante authored
Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
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Nick Piggin authored
mapping->tree_lock has no read lockers. convert the lock from an rwlock to a spinlock. Signed-off-by:
Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
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Nick Piggin authored
Combine page_cache_get_speculative with lockless radix tree lookups to introduce lockless page cache lookups (ie. no mapping->tree_lock on the read-side). The only atomicity changes this introduces is that the gang pagecache lookup functions now behave as if they are implemented with multiple find_get_page calls, rather than operating on a snapshot of the pages. In practice, this atomicity guarantee is not used anyway, and it is to replace individual lookups, so these semantics are natural. Signed-off-by:
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Nick Piggin authored
If we can be sure that elevating the page_count on a pagecache page will pin it, we can speculatively run this operation, and subsequently check to see if we hit the right page rather than relying on holding a lock or otherwise pinning a reference to the page. This can be done if get_page/put_page behaves consistently throughout the whole tree (ie. if we "get" the page after it has been used for something else, we must be able to free it with a put_page). Actually, there is a period where the count behaves differently: when the page is free or if it is a constituent page of a compound page. We need an atomic_inc_not_zero operation to ensure we don't try to grab the page in either case. This patch introduces the core locking protocol to the pagecache (ie. adds page_cache_get_speculative, and tweaks some update-side code to make it work). Thanks to Hugh for pointing out an improvement to the algorithm setting page_count to zero when we have control of all references, in order to hold off speculative getters. [kamezawa.hiroyu@jp.fujitsu.com: fix migration_entry_wait()] [hugh@veritas.com: fix add_to_page_cache] [akpm@linux-foundation.org: repair a comment] Signed-off-by:
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by:
Hugh Dickins <hugh@veritas.com> Acked-by:
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Nick Piggin authored
Introduce gang_lookup_slot() and gang_lookup_slot_tag() functions, which are used by lockless pagecache. Signed-off-by:
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Nick Piggin authored
radix_tree_next_hole() is implemented as a series of radix_tree_lookup()s. So it can be called locklessly, under rcu_read_lock(). Signed-off-by:
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Nick Piggin authored
Signed-off-by:
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Nick Piggin authored
Use get_user_pages_fast in splice. This reverts some mmap_sem batching there, however the biggest problem with mmap_sem tends to be hold times blocking out other threads rather than cacheline bouncing. Further: on architectures that implement get_user_pages_fast without locks, mmap_sem can be avoided completely anyway. Signed-off-by:
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Nick Piggin authored
Use get_user_pages_fast in the common/generic block and fs direct IO paths. Signed-off-by:
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Nick Piggin authored
Implement get_user_pages_fast without locking in the fastpath on x86. Do an optimistic lockless pagetable walk, without taking mmap_sem or any page table locks or even mmap_sem. Page table existence is guaranteed by turning interrupts off (combined with the fact that we're always looking up the current mm, means we can do the lockless page table walk within the constraints of the TLB shootdown design). Basically we can do this lockless pagetable walk in a similar manner to the way the CPU's pagetable walker does not have to take any locks to find present ptes. This patch (combined with the subsequent ones to convert direct IO to use it) was found to give about 10% performance improvement on a 2 socket 8 core Intel Xeon system running an OLTP workload on DB2 v9.5 "To test the effects of the patch, an OLTP workload was run on an IBM x3850 M2 server with 2 processors (quad-core Intel Xeon processors at 2.93 GHz) using IBM DB2 v9.5 running Linux 2.6.24rc7 kernel. Comparing runs with and without the patch resulted in an overall performance benefit of ~9.8%. Correspondingly, oprofiles showed that samples from __up_read and __down_read routines that is seen during thread contention for system resources was reduced from 2.8% down to .05%. Monitoring the /proc/vmstat output from the patched run showed that the counter for fast_gup contained a very high number while the fast_gup_slow value was zero." (fast_gup is the old name for get_user_pages_fast, fast_gup_slow is a counter we had for the number of times the slowpath was invoked). The main reason for the improvement is that DB2 has multiple threads each issuing direct-IO. Direct-IO uses get_user_pages, and thus the threads contend the mmap_sem cacheline, and can also contend on page table locks. I would anticipate larger performance gains on larger systems, however I think DB2 uses an adaptive mix of threads and processes, so it could be that thread contention remains pretty constant as machine size increases. In which case, we stuck with "only" a 10% gain. The downside of using get_user_pages_fast is that if there is not a pte with the correct permissions for the access, we end up falling back to get_user_pages and so the get_user_pages_fast is a bit of extra work. However this should not be the common case in most performance critical code. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: build fix] [akpm@linux-foundation.org: Kconfig fix] [akpm@linux-foundation.org: Makefile fix/cleanup] [akpm@linux-foundation.org: warning fix] Signed-off-by:
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