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Subject[PATCH -tip v2 0/5] kprobes: batch (un)optimization support

Here is the 2nd version of batch optimizing patch series.

Since current kprobes jump optimization calls stop_machine() for each
probe, it can make a lot latency noise when (un)registering a lot of
probes (~1000) at once. For example, on 4 core Xeon, 256 probes
optimization takes 770us in average (max 3.3ms).
This patch series introduces batch (un)optimization which modifies
code with just one stop_machine(), and it improves optimization time
to 90us in average (max 330us).

- Introduce text_poke_smp_batch() which modifies multiple
codes with one stop_machine().
- Limit how many probes can be (un)optimized at once.
- Introduce delayed unoptimization for batch processing.

text_poke_smp_batch() also helps Jason's Jump label to reduce
its overhead coming from text_poke_smp().

Changes in v2:
- Add kprobes selftest bugfix patch.
- Add some comments about locks according to Mathieu's comment.
- Allocate working buffers when initializing kprobes, instead of
using static arraies.
- Merge max optimization limit patch into batch optimizing patch.

Thank you,


Masami Hiramatsu (5):
kprobes: Support delayed unoptimization
kprobes/x86: Use text_poke_smp_batch
x86: Introduce text_poke_smp_batch() for batch-code modifying
[CLEANUP] kprobes: Remove redundant text_mutex lock in optimize
[BUGFIX] kprobes: Fix selftest to clear flags field for reusing probes

arch/x86/include/asm/alternative.h | 7 +
arch/x86/include/asm/kprobes.h | 4
arch/x86/kernel/alternative.c | 49 +++-
arch/x86/kernel/kprobes.c | 114 +++++++++
include/linux/kprobes.h | 4
kernel/kprobes.c | 442 ++++++++++++++++++++++++------------
kernel/test_kprobes.c | 12 +
7 files changed, 464 insertions(+), 168 deletions(-)

Masami Hiramatsu

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