linux/arch
Daniel Borkmann 7e3f977edd perf, events: add non-linear data support for raw records
This patch adds support for non-linear data on raw records. It
extends raw records to have one or multiple fragments that will
be written linearly into the ring slot, where each fragment can
optionally have a custom callback handler to walk and extract
complex, possibly non-linear data.

If a callback handler is provided for a fragment, then the new
__output_custom() will be used instead of __output_copy() for
the perf_output_sample() part. perf_prepare_sample() does all
the size calculation only once, so perf_output_sample() doesn't
need to redo the same work anymore, meaning real_size and padding
will be cached in the raw record. The raw record becomes 32 bytes
in size without holes; to not increase it further and to avoid
doing unnecessary recalculations in fast-path, we can reuse
next pointer of the last fragment, idea here is borrowed from
ZERO_OR_NULL_PTR(), which should keep the perf_output_sample()
path for PERF_SAMPLE_RAW minimal.

This facility is needed for BPF's event output helper as a first
user that will, in a follow-up, add an additional perf_raw_frag
to its perf_raw_record in order to be able to more efficiently
dump skb context after a linear head meta data related to it.
skbs can be non-linear and thus need a custom output function to
dump buffers. Currently, the skb data needs to be copied twice;
with the help of __output_custom() this work only needs to be
done once. Future users could be things like XDP/BPF programs
that work on different context though and would thus also have
a different callback function.

The few users of raw records are adapted to initialize their frag
data from the raw record itself, no change in behavior for them.
The code is based upon a PoC diff provided by Peter Zijlstra [1].

  [1] http://thread.gmane.org/gmane.linux.network/421294

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-15 14:23:56 -07:00
..
alpha tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
arc ARC Fix for 4.7-rc6 2016-06-30 09:53:43 -07:00
arm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-07-06 10:35:22 -07:00
arm64 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-06-30 05:03:36 -04:00
avr32 tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
blackfin printk/nmi: generic solution for safe printk in NMI 2016-05-20 17:58:30 -07:00
c6x asm-generic patch for 4.7 2016-05-24 15:24:37 -07:00
cris tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
frv tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
h8300 Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
hexagon tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
ia64 fix up initial thread stack pointer vs thread_info confusion 2016-06-24 17:07:33 -07:00
m32r Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
m68k tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
metag tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
microblaze tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
mips MIPS: Fix possible corruption of cache mode by mprotect. 2016-07-02 01:51:39 +02:00
mn10300 Merge branch 'akpm' (patches from Andrew) 2016-06-24 19:08:33 -07:00
nios2 nios2: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
openrisc tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
parisc parisc: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
powerpc powerpc fixes for 4.7 #5 2016-07-02 17:47:54 -07:00
s390 perf, events: add non-linear data support for raw records 2016-07-15 14:23:56 -07:00
score score: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
sh sh: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
sparc sparc: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
tile Merge branch 'akpm' (patches from Andrew) 2016-06-24 19:08:33 -07:00
um tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
unicore32 unicore32: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
x86 perf, events: add non-linear data support for raw records 2016-07-15 14:23:56 -07:00
xtensa tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
.gitignore
Kconfig Clarify naming of thread info/stack allocators 2016-06-24 15:09:37 -07:00