This patch adds support for taken branch sampling, i.e, the
PERF_SAMPLE_BRANCH_STACK feature to perf report. In other
words, to display histograms based on taken branches rather
than executed instructions addresses.
The new option is called -b and it takes no argument. To
generate meaningful output, the perf.data must have been
obtained using perf record -b xxx ... where xxx is a branch
filter option.
The output shows symbols, modules, sorted by 'who branches
where' the most often. The percentages reported in the first
column refer to the total number of branches captured and
not the usual number of samples.
Here is a quick example.
Here branchy is simple test program which looks as follows:
void f2(void)
{}
void f3(void)
{}
void f1(unsigned long n)
{
if (n & 1UL)
f2();
else
f3();
}
int main(void)
{
unsigned long i;
for (i=0; i < N; i++)
f1(i);
return 0;
}
Here is the output captured on Nehalem, if we are
only interested in user level function calls.
$ perf record -b any_call,u -e cycles:u branchy
$ perf report -b --sort=symbol
52.34% [.] main [.] f1
24.04% [.] f1 [.] f3
23.60% [.] f1 [.] f2
0.01% [k] _IO_new_file_xsputn [k] _IO_file_overflow
0.01% [k] _IO_vfprintf_internal [k] _IO_new_file_xsputn
0.01% [k] _IO_vfprintf_internal [k] strchrnul
0.01% [k] __printf [k] _IO_vfprintf_internal
0.01% [k] main [k] __printf
About half (52%) of the call branches captured are from main()
-> f1(). The second half (24%+23%) is split in two equal shares
between f1() -> f2(), f1() ->f3(). The output is as expected
given the code.
It should be noted, that using -b in perf record does not
eliminate information in the perf.data file. Consequently, a
typical profile can also be obtained by perf report by simply
not using its -b option.
It is possible to sort on branch related columns:
- dso_from, symbol_from
- dso_to, symbol_to
- mispredict
Signed-off-by: Roberto Agostino Vitillo <ravitillo@lbl.gov>
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: acme@redhat.com
Cc: robert.richter@amd.com
Cc: ming.m.lin@intel.com
Cc: andi@firstfloor.org
Cc: asharma@fb.com
Cc: vweaver1@eecs.utk.edu
Cc: khandual@linux.vnet.ibm.com
Cc: dsahern@gmail.com
Link: http://lkml.kernel.org/r/1328826068-11713-14-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With branch stack sampling, it is possible to filter by priv levels.
In system-wide mode, that means it is possible to capture only user
level branches. The builtin SW LBR filter needs to disassemble code
based on LBR captured addresses. For that, it needs to know the task
the addresses are associated with. Because of context switches, the
content of the branch stack buffer may contain addresses from
different tasks.
We need a callback on context switch to either flush the branch stack
or save it. This patch adds a new callback in struct pmu which is called
during context switches. The callback is called only when necessary.
That is when a system-wide context has, at least, one event which
uses PERF_SAMPLE_BRANCH_STACK. The callback is never called for
per-thread context.
In this version, the Intel x86 code simply flushes (resets) the LBR
on context switches (fills it with zeroes). Those zeroed branches are
then filtered out by the SW filter.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-11-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds an internal sofware filter to complement
the (optional) LBR hardware filter.
The software filter is necessary:
- as a substitute when there is no HW LBR filter (e.g., Atom, Core)
- to complement HW LBR filter in case of errata (e.g., Nehalem/Westmere)
- to provide finer grain filtering (e.g., all processors)
Sometimes the LBR HW filter cannot distinguish between two types
of branches. For instance, to capture syscall as CALLS, it is necessary
to enable the LBR_FAR filter which will also capture JMP instructions.
Thus, a second pass is necessary to filter those out, this is what the
SW filter can do.
The SW filter is built on top of the internal x86 disassembler. It
is a best effort filter especially for user level code. It is subject
to the availability of the text page of the program.
The SW filter is enabled on all Intel processors. It is bypassed
when the user is capturing all branches at all priv levels.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-9-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If precise sampling is enabled on Intel x86 then perf_event uses PEBS.
To correct for the off-by-one error of PEBS, perf_event uses LBR when
precise_sample > 1.
On Intel x86 PERF_SAMPLE_BRANCH_STACK is implemented using LBR,
therefore both features must be coordinated as they may not
configure LBR the same way.
For PEBS, LBR needs to capture all branches at the priv level of
the associated event.
This patch checks that the branch type and priv level of BRANCH_STACK
is compatible with that of the PEBS LBR requirement, thereby allowing:
$ perf record -b any,u -e instructions:upp ....
But:
$ perf record -b any_call,u -e instructions:upp
Is not possible.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-5-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The Intel LBR on some recent processor is capable
of filtering branches by type. The filter is configurable
via the LBR_SELECT MSR register.
There are limitation on how this register can be used.
On Nehalem/Westmere, the LBR_SELECT is shared by the two HT threads
when HT is on. It is private to each core when HT is off.
On SandyBridge, the LBR_SELECT register is private to each thread
when HT is on. It is private to each core when HT is off.
The kernel must manage the sharing of LBR_SELECT. It allows
multiple users on the same logical CPU to use LBR_SELECT as
long as they program it with the same value. Across sibling
CPUs (HT threads), the same restriction applies on NHM/WSM.
This patch implements this sharing logic by leveraging the
mechanism put in place for managing the offcore_response
shared MSR.
We modify __intel_shared_reg_get_constraints() to cause
x86_get_event_constraint() to be called because LBR may
be associated with events that may be counter constrained.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-4-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds the ability to sample taken branches to the
perf_event interface.
The ability to capture taken branches is very useful for all
sorts of analysis. For instance, basic block profiling, call
counts, statistical call graph.
This new capability requires hardware assist and as such may
not be available on all HW platforms. On Intel x86 it is
implemented on top of the Last Branch Record (LBR) facility.
To enable taken branches sampling, the PERF_SAMPLE_BRANCH_STACK
bit must be set in attr->sample_type.
Sampled taken branches may be filtered by type and/or priv
levels.
The patch adds a new field, called branch_sample_type, to the
perf_event_attr structure. It contains a bitmask of filters
to apply to the sampled taken branches.
Filters may be implemented in HW. If the HW filter does not exist
or is not good enough, some arch may also implement a SW filter.
The following generic filters are currently defined:
- PERF_SAMPLE_USER
only branches whose targets are at the user level
- PERF_SAMPLE_KERNEL
only branches whose targets are at the kernel level
- PERF_SAMPLE_HV
only branches whose targets are at the hypervisor level
- PERF_SAMPLE_ANY
any type of branches (subject to priv levels filters)
- PERF_SAMPLE_ANY_CALL
any call branches (may incl. syscall on some arch)
- PERF_SAMPLE_ANY_RET
any return branches (may incl. syscall returns on some arch)
- PERF_SAMPLE_IND_CALL
indirect call branches
Obviously filter may be combined. The priv level bits are optional.
If not provided, the priv level of the associated event are used. It
is possible to collect branches at a priv level different from the
associated event. Use of kernel, hv priv levels is subject to permissions
and availability (hv).
The number of taken branch records present in each sample may vary based
on HW, the type of sampled branches, the executed code. Therefore
each sample contains the number of taken branches it contains.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-2-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cherry picked fixes from perf/core, together with the kernel fix (1018faa),
the sampling tools (top, record) are back working on AMD systems.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If threads in a multi-threaded process have names shorter than the main
thread the comm for the named threads is not properly terminated.
E.g., for the process 'namedthreads' where each thread is named noploop%d
where %d is the thread number:
Before:
perf script -f comm,tid,ip,sym,dso
noploop:4ads 21616 400a49 noploop (/tmp/namedthreads)
The 'ads' in the thread comm bleeds over from the process name.
After:
perf script -f comm,tid,ip,sym,dso
noploop:4 21616 400a49 noploop (/tmp/namedthreads)
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1330111898-68071-1-git-send-email-dsahern@gmail.com
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Here are some trivial NTFS changes (a spelling fix and two use before
NULL check cases found by Coverity as well as an update in MAINTAINERS
for the path to the ntfs git repo) together with a simple LDM fix for
parsing fragmented VBLKs.
* git://git.kernel.org/pub/scm/linux/kernel/git/aia21/ntfs:
NTFS: Update git repo path in MAINTAINERS file.
LDM: Fix reassembly of extended VBLKs.
NTFS: Correct two spelling errors "dealocate" to "deallocate" in mft.c.
NTFS: Do not dereference pointer before checking for NULL.
NTFS: Remove unused variable.
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mce/AMD: Fix UP build error
x86: Specify a size for the cmp in the NMI handler
x86/nmi: Test saved %cs in NMI to determine nested NMI case
x86/amd: Fix L1i and L2 cache sharing information for AMD family 15h processors
x86/microcode: Remove noisy AMD microcode warning
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Handle pending irqs in irq_startup()
genirq: Unmask oneshot irqs when thread was not woken
The new is_compat_task() define for the !COMPAT case in
include/linux/compat.h conflicts with a similar define in
arch/s390/include/asm/compat.h.
This is the minimal patch which fixes the build issues.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Two fixes to fix a memory corruption bug when WC pages never get
converted back to WB but end up being recycled in the general memory
pool as WC.
There is a better way of fixing this, but there is not enough time to do
the full benchmarking to pick one of the right options - so picking the
one that favors stability for right now.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* tag 'stable/for-linus-fixes-3.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/pat: Disable PAT support for now.
xen/setup: Remove redundant filtering of PTE masks.
1) ICMP sockets leave err uninitialized but we try to return it for the
unsupported MSG_OOB case, reported by Dave Jones.
2) Add new Zaurus device ID entries, from Dave Jones.
3) Pointer calculation in hso driver memset is wrong, from Dan
Carpenter.
4) ks8851_probe() checks unsigned value as negative, fix also from Dan
Carpenter.
5) Fix crashes in atl1c driver due to TX queue handling, from Eric
Dumazet. I anticipate some TX side locking fixes coming in the near
future for this driver as well.
6) The inline directive fix in Bluetooth which was breaking the build
only with very new versions of GCC, from Johan Hedberg.
7) Fix crashes in the ATP CLIP code due to ARP cleanups this merge
window, reported by Meelis Roos and fixed by Eric Dumazet.
8) JME driver doesn't flush RX FIFO correctly, from Guo-Fu Tseng.
9) Some ip6_route_output() callers test the return value for NULL, but
this never happens as the convention is to return a dst entry with
dst->error set. Fixes from RonQing Li.
10) Logitech Harmony 900 should be handled by zaurus driver not
cdc_ether, update white lists and black lists accordingly. From
Scott Talbert.
11) Receiving from certain kinds of devices there won't be a MAC header,
so there is no MAC header to fixup in the IPSEC code, and if we try
to do it we'll crash. Fix from Eric Dumazet.
12) Port type array indexing off-by-one in mlx4 driver, fix from Yevgeny
Petrilin.
13) Fix regression in link-down handling in davinci_emac which causes
all RX descriptors to be freed up and therefore RX to wedge
completely, from Christian Riesch.
14) It took two attempts, but ctnetlink soft lockups seem to be
cured now, from Pablo Neira Ayuso.
15) Endianness bug fix in ENIC driver, from Santosh Nayak.
16) The long ago conversion of the PPP fragmentation code over to
abstracted SKB list handling wasn't perfect, once we get an
out of sequence SKB we don't flush the rest of them like we
should. From Ben McKeegan.
17) Fix regression of ->ip_summed initialization in sfc driver.
From Ben Hutchings.
18) Bluetooth timeout mistakenly using msecs instead of jiffies,
from Andrzej Kaczmarek.
19) Using _sync variant of work cancellation results in deadlocks,
use the non _sync variants instead. From Andre Guedes.
20) Bluetooth rfcomm code had reference counting problems leading
to crashes, fix from Octavian Purdila.
21) The conversion of netem over to classful qdisc handling added
two bugs to netem_dequeue(), fixes from Eric Dumazet.
22) Missing pci_iounmap() in ATM Solos driver. Fix from Julia Lawall.
23) b44_pci_exit() should not have __exit tag since it's invoked from
non-__exit code. From Nikola Pajkovsky.
24) The conversion of the neighbour hash tables over to RCU added a
race, fixed here by adding the necessary reread of tbl->nht, fix
from Michel Machado.
25) When we added VF (virtual function) attributes for network device
dumps, this potentially bloats up the size of the dump of one
network device such that the dump size is too large for the buffer
allocated by properly written netlink applications.
In particular, if you add 255 VFs to a network device, parts of
GLIBC stop working.
To fix this, we add an attribute that is used to turn on these
extended portions of the network device dump. Sophisticaed
applications like 'ip' that want to see this stuff will be changed
to set the attribute, whereas things like GLIBC that don't care
about VFs simply will not, and therefore won't be busted by the
mere presence of VFs on a network device.
Thanks to the tireless work of Greg Rose on this fix.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (53 commits)
sfc: Fix assignment of ip_summed for pre-allocated skbs
ppp: fix 'ppp_mp_reconstruct bad seq' errors
enic: Fix endianness bug.
gre: fix spelling in comments
netfilter: ctnetlink: fix soft lockup when netlink adds new entries (v2)
Revert "netfilter: ctnetlink: fix soft lockup when netlink adds new entries"
davinci_emac: Do not free all rx dma descriptors during init
mlx4_core: Fixing array indexes when setting port types
phy: IC+101G and PHY_HAS_INTERRUPT flag
netdev/phy/icplus: Correct broken phy_init code
ipsec: be careful of non existing mac headers
Move Logitech Harmony 900 from cdc_ether to zaurus
hso: memsetting wrong data in hso_get_count()
netfilter: ip6_route_output() never returns NULL.
ethernet/broadcom: ip6_route_output() never returns NULL.
ipv6: ip6_route_output() never returns NULL.
jme: Fix FIFO flush issue
atm: clip: remove clip_tbl
ipv4: ping: Fix recvmsg MSG_OOB error handling.
rtnetlink: Fix problem with buffer allocation
...
The autofs compat handling fix caused a compile failure when
CONFIG_COMPAT isn't defined.
Instead of adding random #ifdef'fery in autofs, let's just make the
compat helpers earlier to use: without CONFIG_COMPAT, is_compat_task()
just hardcodes to zero.
We could probably do something similar for a number of other cases where
we have #ifdef's in code, but this is the low-hanging fruit.
Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
