Summary:
On Windows, Posix integer file descriptors are a compatibility layer
over native file handles provided by the C runtime. There is a hard
limit on the maximum number of file descriptors that a process can open,
and the limit is 8192. LLD typically doesn't run into this limit because
it opens input files, maps them into memory, and then immediately closes
the file descriptor. This prevents it from running out of FDs.
For various reasons, I'd like to open handles to every input file and
keep them open during linking. That requires migrating MemoryBuffer over
to taking open native file handles instead of integer FDs.
Reviewers: aganea, Bigcheese
Reviewed By: aganea
Subscribers: smeenai, silvas, mehdi_amini, hiraditya, steven_wu, dexonsmith, dang, llvm-commits, zturner
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63453
llvm-svn: 365588
Summary:
For the most part this consists of replacing ${LLVM_TARGETS_TO_BUILD} with
some combination of AllTargets* so that they depend on specific components
of a target backend rather than all of it. The overall effect of this is
that, for example, tools like opt no longer falsely depend on the
disassembler, while tools like llvm-ar no longer depend on the code
generator.
There's a couple quirks to point out here:
* AllTargetsCodeGens is a bit more prevalent than expected. Tools like dsymutil
seem to need it which I was surprised by.
* llvm-xray linked to all the backends but doesn't seem to need any of them.
It builds and passes the tests so that seems to be correct.
* I left gold out as it's not built when binutils is not available so I'm
unable to test it
Reviewers: bogner, JDevlieghere
Reviewed By: bogner
Subscribers: mehdi_amini, mgorny, steven_wu, dexonsmith, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62331
llvm-svn: 361567
That patch is the fix for https://bugs.llvm.org/show_bug.cgi?id=40703
"wrong line number info for obj file compiled with -ffunction-sections"
bug. The problem happened with only .o files. If object file contains
several .text sections then line number information showed incorrectly.
The reason for this is that DwarfLineTable could not detect section which
corresponds to specified address(because address is the local to the
section). And as the result it could not select proper sequence in the
line table. The fix is to pass SectionIndex with the address. So that it
would be possible to differentiate addresses from various sections. With
this fix llvm-objdump shows correct line numbers for disassembled code.
Differential review: https://reviews.llvm.org/D58194
llvm-svn: 354972
Summary:
This reverts D50129 / rL338834: [XRay][tools] Use Support/JSON.h in llvm-xray convert
Abstractions are great.
Readable code is great.
JSON support library is a *good* idea.
However unfortunately, there is an internal detail that one needs
to be aware of in `llvm::json::Object` - it uses `llvm::DenseMap`.
So for **every** `llvm::json::Object`, even if you only store a single `int`
entry there, you pay the whole price of `llvm::DenseMap`.
Unfortunately, it matters for `llvm-xray`.
I was trying to analyse the `llvm-exegesis` analysis mode performance,
and for that i wanted to view the LLVM X-Ray log visualization in Chrome
trace viewer. And the `llvm-xray convert` is sluggish, and sometimes
even ended up being killed by OOM.
`xray-log.llvm-exegesis.lwZ0sT` was acquired from `llvm-exegesis`
(compiled with ` -fxray-instruction-threshold=128`)
analysis mode over `-benchmarks-file` with 10099 points (one full
latency measurement set), with normal runtime of 0.387s.
Timings:
Old: (copied from D58580)
```
$ perf stat -r 5 ./bin/llvm-xray convert -sort -symbolize -instr_map=./bin/llvm-exegesis -output-format=trace_event -output=/tmp/trace.yml xray-log.llvm-exegesis.lwZ0sT
Performance counter stats for './bin/llvm-xray convert -sort -symbolize -instr_map=./bin/llvm-exegesis -output-format=trace_event -output=/tmp/trace.yml xray-log.llvm-exegesis.lwZ0sT' (5 runs):
21346.24 msec task-clock # 1.000 CPUs utilized ( +- 0.28% )
314 context-switches # 14.701 M/sec ( +- 59.13% )
1 cpu-migrations # 0.037 M/sec ( +-100.00% )
2181354 page-faults # 102191.251 M/sec ( +- 0.02% )
85477442102 cycles # 4004415.019 GHz ( +- 0.28% ) (83.33%)
14526427066 stalled-cycles-frontend # 16.99% frontend cycles idle ( +- 0.70% ) (83.33%)
32371533721 stalled-cycles-backend # 37.87% backend cycles idle ( +- 0.27% ) (33.34%)
67896890228 instructions # 0.79 insn per cycle
# 0.48 stalled cycles per insn ( +- 0.03% ) (50.00%)
14592654840 branches # 683631198.653 M/sec ( +- 0.02% ) (66.67%)
212207534 branch-misses # 1.45% of all branches ( +- 0.94% ) (83.34%)
21.3502 +- 0.0585 seconds time elapsed ( +- 0.27% )
```
New:
```
$ perf stat -r 9 ./bin/llvm-xray convert -sort -symbolize -instr_map=./bin/llvm-exegesis -output-format=trace_event -output=/tmp/trace.yml xray-log.llvm-exegesis.lwZ0sT
Performance counter stats for './bin/llvm-xray convert -sort -symbolize -instr_map=./bin/llvm-exegesis -output-format=trace_event -output=/tmp/trace.yml xray-log.llvm-exegesis.lwZ0sT' (9 runs):
7178.38 msec task-clock # 1.000 CPUs utilized ( +- 0.26% )
182 context-switches # 25.402 M/sec ( +- 28.84% )
0 cpu-migrations # 0.046 M/sec ( +- 70.71% )
33701 page-faults # 4694.994 M/sec ( +- 0.88% )
28761053971 cycles # 4006833.933 GHz ( +- 0.26% ) (83.32%)
2028297997 stalled-cycles-frontend # 7.05% frontend cycles idle ( +- 1.61% ) (83.32%)
10773154901 stalled-cycles-backend # 37.46% backend cycles idle ( +- 0.38% ) (33.36%)
36199132874 instructions # 1.26 insn per cycle
# 0.30 stalled cycles per insn ( +- 0.03% ) (50.02%)
6434504227 branches # 896420204.421 M/sec ( +- 0.03% ) (66.68%)
73355176 branch-misses # 1.14% of all branches ( +- 1.46% ) (83.33%)
7.1807 +- 0.0190 seconds time elapsed ( +- 0.26% )
```
So using `llvm::json` nearly triples run-time on that test case.
(+3x is times, not percent.)
Memory:
Old:
```
total runtime: 39.88s.
bytes allocated in total (ignoring deallocations): 79.07GB (1.98GB/s)
calls to allocation functions: 33267816 (834135/s)
temporary memory allocations: 5832298 (146235/s)
peak heap memory consumption: 9.21GB
peak RSS (including heaptrack overhead): 147.98GB
total memory leaked: 1.09MB
```
New:
```
total runtime: 17.42s.
bytes allocated in total (ignoring deallocations): 5.12GB (293.86MB/s)
calls to allocation functions: 21382982 (1227284/s)
temporary memory allocations: 232858 (13364/s)
peak heap memory consumption: 350.69MB
peak RSS (including heaptrack overhead): 2.55GB
total memory leaked: 79.95KB
```
Diff:
```
total runtime: -22.46s.
bytes allocated in total (ignoring deallocations): -73.95GB (3.29GB/s)
calls to allocation functions: -11884834 (529155/s)
temporary memory allocations: -5599440 (249307/s)
peak heap memory consumption: -8.86GB
peak RSS (including heaptrack overhead): 0B
total memory leaked: -1.01MB
```
So using `llvm::json` increases *peak* memory consumption on *this* testcase ~+27x.
And total allocation count +15x. Both of these numbers are times, *not* percent.
And note that memory usage is clearly unbound with `llvm::json`, it directly depends
on the length of the log, so peak memory consumption is always increasing.
This isn't so with the dumb code, there is no accumulating memory consumption,
peak memory consumption is fixed. Naturally, that means it will handle *much*
larger logs without OOM'ing.
Readability is good, but the price is simply unacceptable here.
Too bad none of this analysis was done as part of the development/review D50129 itself.
Reviewers: dberris, kpw, sammccall
Reviewed By: dberris
Subscribers: riccibruno, hans, courbet, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58584
llvm-svn: 354764
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
In a lot of places an empty string was passed as the ErrorBanner to
logAllUnhandledErrors. This patch makes that argument optional to
simplify the call sites.
llvm-svn: 346604
Summary:
This change cuts across LLVM and compiler-rt to add support for
rendering custom events in the XRayRecord type, to allow for including
user-provided annotations in the output YAML (as raw bytes).
This work enables us to add custom event and typed event records into
the `llvm::xray::Trace` type for user-provided events. This can then be
programmatically handled through the C++ API and can be included in some
of the tooling as well. For now we support printing the raw data we
encounter in the custom events in the converted output.
Future work will allow us to start interpreting these custom and typed
events through a yet-to-be-defined API for extending the trace analysis
library.
Reviewers: mboerger
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D54139
llvm-svn: 346214
top argument when superior to the instrumentated code list capacity can lead to a segfault.
Reviewers: dberris
Reviewed By: dberris
Differential Revision: https://reviews.llvm.org/D52224
llvm-svn: 342461
Summary:
In this change, we implement a `BlockPrinter` which orders records in a
Block that's been indexed by the `BlockIndexer`. This is used in the
`llvm-xray fdr-dump` tool which ties together the various types and
utilities we've been working on, to allow for inspection of XRay FDR
mode traces both with and without verification.
This change is the final step of the refactoring of D50441.
Reviewers: mboerger, eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51846
llvm-svn: 341887
Summary:
This change removes the ad-hoc implementation used by llvm-xray's
`convert` subcommand to generate JSON encoded catapult (AKA Chrome
Trace Viewer) trace output, to instead use the JSON encoder now in the
Support library.
Reviewers: kpw, zturner, eizan
Reviewed By: kpw
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D50129
llvm-svn: 338834
Summary:
llvm-xray changes:
- account-mode - process-id {...} shows after thread-id
- convert-mode - process {...} shows after thread
- parses FDR and basic mode pid entries
- Checks version number for FDR log parsing.
Basic logging changes:
- Update header version from 2 -> 3
FDR logging changes:
- Update header version from 2 -> 3
- in writeBufferPreamble, there is an additional PID Metadata record (after thread id record and tsc record)
Test cases changes:
- fdr-mode.cc, fdr-single-thread.cc, fdr-thread-order.cc modified to catch process id output in the log.
Reviewers: dberris
Reviewed By: dberris
Subscribers: hiraditya, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D49153
llvm-svn: 336974
NFC here, this just raises some platform specific ifdef hackery
out of a class and creates proper platform-independent typedefs
for the relevant things. This allows these typedefs to be
reused in other places without having to reinvent this preprocessor
logic.
llvm-svn: 334294
Provide some free functions to reduce verbosity of endian-writing
a single value, and replace the endianness template parameter with
a field.
Part of PR37466.
Differential Revision: https://reviews.llvm.org/D47032
llvm-svn: 332757
Summary:
This brings the filenames in accordance to the style guide and LLVM
conventions for C++ filenames.
As suggested by rnk@ in D46068.
Reviewers: rnk
Subscribers: mgorny, mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D46301
llvm-svn: 331321
Summary:
r327219 added wrappers to std::sort which randomly shuffle the container before sorting.
This will help in uncovering non-determinism caused due to undefined sorting
order of objects having the same key.
To make use of that infrastructure we need to invoke llvm::sort instead of std::sort.
Note: This patch is one of a series of patches to replace *all* std::sort to llvm::sort.
Refer the comments section in D44363 for a list of all the required patches.
Reviewers: JDevlieghere, zturner, echristo, dberris, friss
Reviewed By: echristo
Subscribers: gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D45141
llvm-svn: 328943
Summary:
Processing 2 GB XRay traces with "llvm-xray convert -symbolize" needs to
go over each trace record and symbolize the function name refered to by
its ID. Currently this happens by asking the LLVM symbolizer code every
single time. A simple cache can save around 30 minutes of processing of
that trace.
llvm-xray's resident memory usage increased negligibly with this cache.
Reviewers: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43896
llvm-svn: 326407
Summary:
It was a copy-paste typo, sorting only to the 90th percentile twice.
Now, it only sorts the array prefix once, and extracts what we need.
Reviewers: dberris, kpw, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42690
llvm-svn: 323800
Minimal tool to convert xray traces to Chrome's Trace Event Format.
Summary:
Make use of Chrome Trace Event format's Duration events and stack frame dict to
produce Json files that chrome://tracing can visualize from xray function call
traces. Trace Event format is more robust and has several features like
argument logging, function categorization, multi process traces, etc. that we
can add as needed. Duration events cover an important base case.
Part of this change is rearranging the code so that the TrieNode data structure
can be used from multiple tools and can carry parameterized baggage on the
nodes. I put the actual behavior changes in llvm-xray convert exclusively.
Exploring the trace of instrumented llc was pretty nifty if overwhelming.
I can envision this being very useful for analyzing contention scenarios or
tuning parameters like batch sizes in a producer consumer queue. For more
targeted traces likemthis, let's talk about how we want to approach trace
pruning.
Reviewers: dberris, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D39362
llvm-svn: 317531
Summary:
As the first step to allow analysis and visualization of xray collected data,
allow using the llvm-xray stacks tool to emit a complete listing of stacks in
the format consumable by a flamegraph tool.
Possible follow up formats include chrome trace viewer format and sql load
files.
As a POC, I'm able to generate flamegraphs of an xray instrumented llc compiling
hello world.
Reviewers: dberris, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38650
llvm-svn: 315635
Summary:
A new FDR metadata record will support logging a function call argument;
appending multiple metadata records will represent a sequence of arguments
meaning that "holes" are not representable by the buffer format. Each
call argument is currently a 64-bit value (useful for "this" pointers and
synchronization objects).
If present, we put this argument to the function call "entry" record it
belongs to, and alter its type to notify the user of its presence.
Reviewers: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32840
llvm-svn: 314269
Summary:
This change adds support for explicit tail-exit records to be written by
the XRay runtime. This lets us differentiate the tail exit
records/events in the log, and allows us to treat those exit events
especially in the future. For now we allow printing those out in YAML
(and reading them in).
Reviewers: kpw, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D37964
llvm-svn: 313514
Most callers were not expecting the exit(0) and trying to exit with a
different value.
This also adds back the call to cl::PrintHelpMessage in llvm-ar.
llvm-svn: 312761
Second try after fixing a code san problem with iterator reference types.
This change introduces a subcommand to the llvm-xray tool called
"stacks" which allows for analysing XRay traces provided as inputs and
accounting time to stacks instead of just individual functions. This
gives us a more precise view of where in a program the latency is
actually attributed.
The tool uses a trie data structure to keep track of the caller-callee
relationships as we process the XRay traces. In particular, we keep
track of the function call stack as we enter functions. While we're
doing this we're adding nodes in a trie and indicating a "calls"
relatinship between the caller (current top of the stack) and the callee
(the new top of the stack). When we push function ids onto the stack, we
keep track of the timestamp (TSC) for the enter event.
When exiting functions, we are able to account the duration by getting
the difference between the timestamp of the exit event and the
corresponding entry event in the stack. This works even if we somehow
miss the exit events for intermediary functions (i.e. if the exit event
is not cleanly associated with the enter event at the top of the stack).
The output of the tool currently provides just the top N leaf functions
that contribute the most latency, and the top N stacks that have the
most frequency. In the future we can provide more sophisticated query
mechanisms and potentially an export to database feature to make offline
analysis of the stack traces possible with existing tools.
Differential revision: D34863
llvm-svn: 312733
This change introduces a subcommand to the llvm-xray tool called
"stacks" which allows for analysing XRay traces provided as inputs and
accounting time to stacks instead of just individual functions. This
gives us a more precise view of where in a program the latency is
actually attributed.
The tool uses a trie data structure to keep track of the caller-callee
relationships as we process the XRay traces. In particular, we keep
track of the function call stack as we enter functions. While we're
doing this we're adding nodes in a trie and indicating a "calls"
relatinship between the caller (current top of the stack) and the callee
(the new top of the stack). When we push function ids onto the stack, we
keep track of the timestamp (TSC) for the enter event.
When exiting functions, we are able to account the duration by getting
the difference between the timestamp of the exit event and the
corresponding entry event in the stack. This works even if we somehow
miss the exit events for intermediary functions (i.e. if the exit event
is not cleanly associated with the enter event at the top of the stack).
The output of the tool currently provides just the top N leaf functions
that contribute the most latency, and the top N stacks that have the
most frequency. In the future we can provide more sophisticated query
mechanisms and potentially an export to database feature to make offline
analysis of the stack traces possible with existing tools.
llvm-svn: 312426
Summary:
Before this patch, llvm-xray account will assume that thread stacks will
not be empty. Unfortunately there are cases where an instrumented
function will see a call to `fork()` which will cause the child process
to not see the start of the function, but only see the end of the
function. The tooling cannot assume that threads will always have
perfect stacks, and so we change it to support this reality.
Reviewers: dblaikie
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31870
llvm-svn: 312204
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.
Differential Revision: https://reviews.llvm.org/D33843
llvm-svn: 304864
Summary:
This is a tool for comparing the function graphs produced by the
llvm-xray graph too. It takes the form of a new subcommand of the
llvm-xray tool 'graph-diff'.
This initial version of the patch is very rough, but it is close to
feature complete.
Depends on D29363
Reviewers: dblaikie, dberris
Reviewed By: dberris
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D29320
llvm-svn: 301160
Summary:
This allows us to, if the symbol names are available in the binary, be
able to provide the function name in the YAML output.
Reviewers: dblaikie, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32153
llvm-svn: 300624
Summary:
Assertions assuming that function calls may not have zero durations do
not seem to hold in the wild. There are valid cases where the conversion
of the tsc counters end up becoming zero-length durations. These
assertions don't really hold and the algorithms don't need those to be
true for them to work.
Reviewers: dblaikie, echristo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31519
llvm-svn: 299150
Summary:
Currently the llvm-xray commandline tool fails to handle the case for
when no subcommand is provided in a graceful manner. This fixes that to
print the help message explaining the subcommands and the available
options.
Reviewers: pcc, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31409
llvm-svn: 298975
Summary:
In Preparation for graph comparison, this patch breaks out the color
choice code from xray-graph into a library and adds polynomials for
the Sequential and Difference sets from ColorBrewer.
Depends on D29005
Reviewers: dblaikie, chandlerc, dberris
Reviewed By: dberris
Subscribers: chandlerc, llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D29363
llvm-svn: 296210
Summary:
The file type packs function trace data onto disk from potentially multiple
threads that are aggregated and flushed during the course of an instrumented
program's runtime.
It is named FDR mode or Flight Data recorder as an analogy to plane
blackboxes, which instrument a running system without access to IO.
The writer code is defined in compiler-rt in xray_fdr_logging.h/cc
Reviewers: rSerge, kcc, dberris
Reviewed By: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29697
llvm-svn: 295397
Summary:
The YAML output produced by llvm-xray is supposed to be wrapped at the
arbitrary default of 70 columns set by `yaml:Output`. Unfortunately,
the wrapping is rather unpredictable, and can easily go past the set
number of columns, depending on the execution environment.
To make the YAML output environment-independent, disable wrapping
instead.
Reviewers: dberris
Reviewed By: dberris
Subscribers: fhahn, llvm-commits
Differential Revision: https://reviews.llvm.org/D29962
llvm-svn: 295116
