Re: [PATCH] Immediate Value - Architecture Independent Code Deferred Sync

Mathieu Desnoyers
2007-07-15T01:33:12Z

Please drop, wrong thread. Will repost in the right one.

* Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote:
> Linux Kernel Markers - Architecture Independent Code Deferred Sync
>
> Upon marker probe_unregister, we delay call to synchronize_sched() to
> accelerate mass unregistration (only when there is no more reference to a
> give module do we call synchronize_sched()). However, we need to make sure
> every critical region have ended before we re-arm a marker that has been
> unregistered and then registered back with a different probe data.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> CC: Christoph Hellwig <hch@infradead.org>
> ---
> kernel/marker.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> Index: linux-2.6-lttng/kernel/marker.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/marker.c 2007-07-14 19:38:11.000000000 -0400
> +++ linux-2.6-lttng/kernel/marker.c 2007-07-14 19:46:25.000000000 -0400
> @@ -30,11 +30,21 @@ extern struct __mark_marker __stop___mar
>
> /*
> * module_mutex nests inside markers_mutex. Markers mutex protects the builtin
> - * and module markers, and the hash table.
> + * and module markers, the hash table and deferred_sync.
> */
> DEFINE_MUTEX(markers_mutex);
>
> /*
> + * Marker deferred synchronization.
> + * Upon marker probe_unregister, we delay call to synchronize_sched() to
> + * accelerate mass unregistration (only when there is no more reference to a
> + * give module do we call synchronize_sched()). However, we need to make sure
> + * every critical region have ended before we re-arm a marker that has been
> + * unregistered and then registered back with a different probe data.
> + */
> +static int deferred_sync;
> +
> +/*
> * Marker hash table, containing the active markers.
> * Protected by module_mutex.
> */
> @@ -303,8 +313,10 @@ static inline void __marker_update_probe
> __stop___markers, probe_module, &refcount);
> /* Markers in modules. */
> __marker_update_probes_modules(probe_module, &refcount);
> - if (probe_module && refcount == 0)
> + if (probe_module && refcount == 0) {
> synchronize_sched();
> + deferred_sync = 0;
> + }
> }
>
> #ifdef CONFIG_MODULES
> @@ -353,6 +365,10 @@ int marker_probe_register(const char *na
> ret = -EBUSY;
> goto end;
> }
> + if (deferred_sync) {
> + synchronize_sched();
> + deferred_sync = 0;
> + }
> ret = _add_marker(name, format, probe, pdata);
> if (ret)
> goto end;
> @@ -384,6 +400,7 @@ void *marker_probe_unregister(const char
> /* In what module is the probe handler ? */
> probe_module = __module_text_address((unsigned long)entry->probe);
> pdata = _remove_marker(name);
> + deferred_sync = 1;
> _marker_update_probes(probe_module);
> end:
> mutex_unlock(&markers_mutex);
> @@ -425,6 +442,7 @@ iter_end:
> /* In what module is the probe handler ? */
> probe_module = __module_text_address((unsigned long)entry->probe);
> pdata = _remove_marker(entry->name);
> + deferred_sync = 1;
> _marker_update_probes(probe_module);
> end:
> mutex_unlock(&markers_mutex);
> --
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
> -
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