| Age | Commit message (Collapse) | Author |
|---|
|
Summary:
Before this change, the FDR mode implementation relied on at thread-exit
handling to return buffers back to the (global) buffer queue. This
introduces issues with the initialisation of the thread_local objects
which, even through the use of pthread_setspecific(...) may eventually
call into an allocation function. Similar to previous changes in this
line, we're finding that there is a huge potential for deadlocks when
initialising these thread-locals when the memory allocation
implementation is also xray-instrumented.
In this change, we limit the call to pthread_setspecific(...) to provide
a non-null value to associate to the key created with
pthread_key_create(...). While this doesn't completely eliminate the
potential for the deadlock(s), it does allow us to still clean up at
thread exit when we need to. The change is that we don't need to do more
work when starting and ending a thread's lifetime. We also have a test
to make sure that we actually can safely recycle the buffers in case we
end up re-using the buffer(s) available from the queue on multiple
thread entry/exits.
This change cuts across both LLVM and compiler-rt to allow us to update
both the XRay runtime implementation as well as the library support for
loading these new versions of the FDR mode logging. Version 2 of the FDR
logging implementation makes the following changes:
* Introduction of a new 'BufferExtents' metadata record that's outside
of the buffer's contents but are written before the actual buffer.
This data is associated to the Buffer handed out by the BufferQueue
rather than a record that occupies bytes in the actual buffer.
* Removal of the "end of buffer" records. This is in-line with the
changes we described above, to allow for optimistic logging without
explicit record writing at thread exit.
The optimistic logging model operates under the following assumptions:
* Threads writing to the buffers will potentially race with the thread
attempting to flush the log. To avoid this situation from occuring,
we make sure that when we've finalized the logging implementation,
that threads will see this finalization state on the next write, and
either choose to not write records the thread would have written or
write the record(s) in two phases -- first write the record(s), then
update the extents metadata.
* We change the buffer queue implementation so that once it's handed
out a buffer to a thread, that we assume that buffer is marked
"used" to be able to capture partial writes. None of this will be
safe to handle if threads are racing to write the extents records
and the reader thread is attempting to flush the log. The optimism
comes from the finalization routine being required to complete
before we attempt to flush the log.
This is a fairly significant semantics change for the FDR
implementation. This is why we've decided to update the version number
for FDR mode logs. The tools, however, still need to be able to support
older versions of the log until we finally deprecate those earlier
versions.
Reviewers: dblaikie, pelikan, kpw
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D39526
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@318733 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Summary:
Write out records about logged function call first arguments. D32840
implements the reading of this in llvm-xray.
Reviewers: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32844
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@314378 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Summary:
This change implements support for the custom event logging sleds and
intrinsics at runtime. For now it only supports handling the sleds in
x86_64, with the implementations for other architectures stubbed out to
do nothing.
NOTE: Work in progress, uploaded for exposition/exploration purposes.
Depends on D27503, D30018, and D33032.
Reviewers: echristo, javed.absar, timshen
Subscribers: mehdi_amini, nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D30630
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@302857 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Summary:
Separated the IO and the thread local storage state machine of logging
from the writing of log records once the contents are deterministic.
Finer granularity functions are provided as inline functions in the same
header such that stack does not grow due to the functions being separated.
An executable utility xray_fdr_log_printer is also implemented to use the
finest granularity functions to produce binary test data in the FDR format
with a relatively convenient text input.
For example, one can take a file with textual contents layed out in rows
and feed it to the binary to generate data that llvm-xray convert can then
read. This is a convenient way to build a test suite for llvm-xray convert
to ensure it's robust to the fdr format.
Example:
$cat myFile.txt
NewBuffer : { time = 2 , Tid=5}
NewCPU : { CPU =1 , TSC = 123}
Function : { FuncId = 5, TSCDelta = 3, EntryType = Entry }
Function : { FuncId = 5, TSCDelta = 5, EntryType = Exit}
TSCWrap : { TSC = 678 }
Function : { FuncId = 6, TSCDelta = 0, EntryType = Entry }
Function : { FuncId = 6, TSCDelta = 50, EntryType = Exit }
EOB : { }
$cat myFile.txt | ./bin/xray_fdr_log_printer > /tmp/binarydata.bin
$./bin/llvm-xray convert -output-format=yaml -output=- /tmp/binarydata.bin
yaml format comes out as expected.
Reviewers: dberris, pelikan
Reviewed By: dberris
Subscribers: llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D30850
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@297801 91177308-0d34-0410-b5e6-96231b3b80d8
|
