I am trying to simulate hardware changes such as cache on the application performance. However, what I want is arbitrary applications such as NodeJS, bash shell, java...
build/X86/gem5.opt \
configs/example/se.py \
--cmd /usr/bin/node \
--options /path/to/my/node.js
(1) Is this the correct way? Or do I have to feed an executable binary?
Using the command way, I got the error though:
fatal: syscall epoll_create1 (#291) unimplemented.
I found similar Q1 Q2
(2) If I did right in (1), how can I fix the errors. Maybe more than one unimplemented syscall. The Q2 answer says try gem5 full system model. I have little experience with gem5, so can you give me an example of using gem5 full system model to run a node, bash or whatever application that is not binary but command-line type?
Related
PostgreSQLv14 source code compiled on GCCv12 with --enable-debug.
And Benchmark environment used as HammerDBv4.1 to test OLTP(TPC-C) on PostgreSQL
Here to the goal to identity cache misses(L1, L2 and L3 caches)annotate PostgreSQL source code or Methods() on running PostgreSQL bin's
Tired following commands:
valgrind --tool=cachegrind ./bin/tclsh8.6 ./hammerdbcli auto test_32vu.tcl (not shown PostgreSQL Methods() or calls)
valgrind --tool=cachegrind --trace-children=yes ./usr/local/postgresqlv14/bin/postgres -D /usr/local/postgres/data
example(excepted:Cachegrind: Why so many cache misses?)
But the above command not help out.And also tired with other tools like perf.
Perf also not helped on it :
https://developers.redhat.com/blog/2014/03/10/determining-whether-an-application-has-poor-cache-performance-2#amd_
Please let me know the right way to check annotate source code of cache misses in PostgreSQL by using Valgrind or other tools like perf.
I am trying to capture the profile data of a test run. As the title states, I am running .net core 2.X on CentOS. I am able to generate the *.map files. Grepping through the files' contents, I can see target source code mapped.
Subsequently I run:
dotnet test --no-build &
sudo perf record -p PID -g
After the test run finalizes and running "sudo perf report -f" I can not see any of the target symbols.
I know that dotnet test forks the test load to several subprocesses.
In short, I have two questions:
What am I missing? and does perf keep track of the subprocesses created by the PID under observation?
Thanks!
edit 1
What I have noticed is that the how-to instructions show *.map in the shared object column. My runs don’t. None of the blogs point out that a path has to be given.
Does perf look in /tmp by default for map files?
Edit 2
By launching the test run with the following command: “perf record dotnet test” I have been able to make perf to use the *.map files (they appear in the shared object column of Perf’s report) and generate a reasonable amount of data (as opposed to the tiny amount that I captured before) but the target symbols are still missing. It grabs the newton soft symbols from the same *.map but not my code
I'm attempting to import an SQL dump in PgAdmin 4 using the psql client - However the error message returned is - The system cannnot find the file specified.
Here is a screenshot of my psql client -
The file films.sql is currently stored on my desktop, but I suspect the default location that the psql client accesses is not my desktop? Is there anyway to set the location that the client looks in order to resolve this?
The file SQL is viewable here: https://github.com/datacamp/courses-intro-to-sql/tree/master/datasets
I simply want to get the database on my local machine so that I don't need to store queries in an online learning platform. It would be best if this database is available locally to query and practice on.
I've attempted to execute the whole SQL file as a query on the films database but this does not seem to be working either and returns 'Asynchronous query execution/operation underway.
Query returned successfully in 388 msec.' - However it seems to be the case that the Asynchronous query never completes when I refresh the database.
Please can someone help?
Just give the path to your file:
psql -d my_database -f /path/to/the/file.sql
psql -d my_database -f C:/path/to/the/file.sql
Depending on whether you are on a unix/linux machine or Windows.
Oh, and if you aren't familiar with file paths you may want to take a step back and become more familiar with general computer terminology before diving into a RDBMS. Your learning will be much easier if you have a solid foundation to build upon.
I suspect this question might be moot for the asker at this point, but for anyone else stumbling upon it like I did: the interactive connection info prompts are provided by a batch script (in Windows, I'd guess there's an analogous shell script for Unix) called runpsql.bat, which then just passes your inputs as commandline arguments to the psql.exe executable. I was getting this error because I had migrated my Postgres installation and the batch script was calling a nonexistent path for psql.exe, hence The system cannot find the file specified. I edited runpsql.bat to point to the correct location of psql.exe and that resolved the issue. So for OP, I would look into PgAdmin4 and see where it's (presumably) calling runpsql.bat, then make sure that that calls psql.exe with the correct path.
I am using helios Eclipse for debugging my code in postgresql.
My aim is to know how postgresql uses join algorithms during the join query, so I started to debug nodenestloop.c which is in the Executor folder.
I gave break points in that file, But whenever I try to debug that file, the control goes to main.c and never comes back,How do I constraint the control only to that particular file(nodenestloop.c)
Below are the following fields which I gave in Debug configurations of Helios Eclipse.
C/C++ Application - src/backend/postgres and
project - pgsql
I followed the steps given in the following link for running the program.
https://wiki.postgresql.org/wiki/Working_with_Eclipse#
I even uncheked the field "Start on Start up=main" , but When I do that, The step in and Step over buttons are not activated and the following problem has popped up.
Could not save master table to file '/home/ravi/workspace/.metadata/.plugins/org.eclipse.core.resources/.safetable/org.eclipse.core.resources'.
/home/ravi/workspace/.metadata/.plugins/org.eclipse.core.resources/.safetable/org.eclipse.core.resources (Permission denied)
So I started eclipse using sudo, but this time the following error has come in the console of eclipse.
"root" execution of the PostgreSQL server is not permitted.
The server must be started under an unprivileged user ID to prevent
possible system security compromise. See the documentation for
more information on how to properly start the server.
Could any one help me with this.
Thank you
Problem 1: User ID mismatch
Reading between the lines, it sounds like you're trying to debug a PostgreSQL instance that's running as the postgres user, or a different user ID to your own anyway. Hence your attempt to use sudo.
That's painful, especially when using an IDE like Eclipse. With plain gdb you can just sudo the gdb command to the desired uid, e.g. sudo -u postgres -p 12345 to attach to pid 12345 running as user postgres. This will not work with Eclipse. In fact, running it with sudo has probably left your workspace with some messed up file permissions; run:
sudo chown -R ravi /home/ravi/workspace/
to fix file ownership.
If you want to debug processes under other user IDs with Eclipse, you'll need to figure out how to make Eclipse run gdb with sudo. Do not just run all of Eclipse with sudo.
Problem 2: Trying to run PostgreSQL under the control of Eclipse
This:
"root" execution of the PostgreSQL server is not permitted. The server must be started under an unprivileged user ID to prevent possible system security compromise. See the documentation for more information on how to properly start the server.
suggests that you're also attempting to let Eclipse start postgres directly. That's very useful if you're trying to debug the postmaster, but since you're talking about the query planner it's clear you want to debug a particular backend. Launching the postmaster under Eclipse is useless for that, you'll be attached to the wrong process.
I think you probably need to read the documentation on PostgreSQL's internals:
Tour of PostgreSQL Internals
PostgreSQL internals through pictures
Documentation chapter - internals
Doing it right
Here's what you need to do - rough outline, since I've only used Eclipse for Java development and do my C development with vim and gdb:
Compile a debug build of PostgreSQL (compiled with ./configure --enable-debug and preferably also CFLAGS="-ggdb -Og -fno-omit-frame-pointer"). Specify a --prefix within your homedir, like --prefix=$HOME/postgres-debug
Put your debug build's bin directory first on your PATH, e.g. export PATH=$HOME/postgres-debug/bin:$PATH
initdb -U postgres -D $HOME/postgres-debug-data a new instance of PostgreSQL from your debug build
Start the new instance with PGPORT=5599 pg_ctl -D $HOME/postgres-debug-data -l $HOME/postgres-debug-data.log -w start
Connect with PGPORT=5599 psql postgres
Do whatever setup you need to do
Get the backend process ID with SELECT pg_backend_pid() in a psql session. Leave that session open; it's the one you'll be debugging.
Attach Eclipse's debugger to that process ID, using the Eclipse project that contains the PostgreSQL extension source code you're debugging. Make sure Eclipse is configured so it can find the PostgreSQL source code you compiled with too (no idea how to do that, see the manual).
Set any desired breakpoints and resume execution
In the psql session, do whatever you need to do to make your extension run and hit the breakpoint
When execution pauses at the breakpoint in Eclipse, debug as desired.
Basic misunderstandings?
Also, in case you're really confused about how all this works: PostgreSQL is a client/server application. If you are attempting to debug a client program that uses libpq or odbc, and expecting a breakpoint to trigger in some PostgreSQL backend extension code, that is not going to happen. The client application communicates with PostgreSQL over a TCP/IP socket. It's a separate program. gdb cannot set breakpoints in the PostgreSQL server when it's connected to the client, because they are separate programs. If you want to debug the server, you have to attach gdb to the server. PostgreSQL uses one process per connection, so you have to attach gdb to the correct server process. Which is why I said to use SELECT pg_backend_pid() above, and attach to the process ID.
See the internals documentation linked above, and:
PostgreSQL site - coding
PostgreSQL wiki - developer resources
Developer FAQ
Attaching gdb to a backend on linux/bsd/unix
I also faced similar issue and resolved it after some struggle
I misunderstood the following point under Debugging with child processes in the wiki (https://wiki.postgresql.org/wiki/Working_with_Eclipse).
5."Start postmaster & one instant of postgresql client (for creating one new postgres)"
The above step should be performed from terminal by starting postgres server and one client.
Hope this helps
Once this is done then debugger in eclipse needs to be started for C/C++ Attach to Application
In order to take some development work home I have to be able to run a PostgreSQL database.
I don't want to install anything on the machine at home. Everything should run off the usb drive.
What development tools do you carry on your USB drive?
That question covers pretty much everything else, but I have yet to find a guide to getting postgresql portable. It doesn't seem easy if it's even possible.
So how do I get PostgreSQL portable? Is it even possible?
EDIT:
PostgreSQL Portable works. It's very slow on the usb-drive I have, but it works. I can't recommend doing constant development with it but for what I need it's great.
Perhaps if I pick up a full speed external drive I'll try out virtualization. Given the poor performance of just running the database off this drive, a full virtual OS running off of it would be unusable.
Here's how you can do this on your own:
http://www.postgresonline.com/journal/archives/172-Starting-PostgreSQL-in-windows-without-install.html
An alternate route would be to use something like VirtualBox and just install your development environment (database, whatever) on there.
There are 2 projects to try in 2014: http://sourceforge.net/projects/pgsqlportable/ and http://sourceforge.net/projects/postgresqlportable/?source=recommended.
I can't vouch for the second, but I'm using the first and it works right out of the box.
After unzipping using 7-zip (http://www.7-zip.org/download.html):
1) Run "start service without usuario.bat" ( english translation )
2) Then run "pgadmin3.bat"
The only minimal problem for me was that its in spanish. I've been able to change the language to english by following Change language of system and error messages in PostgreSQL. Using google translate the instructions are:
Description
This is a zip to automatically run postgresql 9.1.0.1 for windows. This version already has pgagent and pldebugger. To run must: 1) unzip
the zip 2) run the "start service without usuario.bat" found in the
pgsql directory within the folder you just unzipped. 3) Optional. If
you want to run the agent works postgresql (pgagent) should only run
the "start pgagent.bat" found in the pgsql directory inside the folder
you just unzipped. 4) Optional. To manage and / or develop the bd you
can run the pgadmin3.bat 5 files) Optional. To stop and / or restart
the server correctly use file "service without stopping usuario.bat"
usuario.bat or restart service without depending on the case.
Now option for Linux (file. Tar.gz). Postgresql portable Linux 9.2
Please use the tickets for your answer bugs.
Username: postgres Password: 123
Just a Note : on a new computer , to get pgadminIII working you may need to add a db. The settings are in attached screenshot.
Hope it helps.
I agree with virtualization solution, but maybe you can find useful this link from portable freeware collection, I have used this locally, not from usb though
1.download and extract : zip version
2.inside pgsql folder create data folder(put any name,I used 'data')
3.initalize data folder: c:\pgsql\bin\initdb.exe -D c:\pgsql\data -U postgres -W -E UTF8 -A scram-sha-256
4.to start/stop see next cmd code that I use (press any key inside it to stop)
c:\pgsql\bin\pg_ctl.exe -D c:\pgsql\data -l logfile start
pause
c:\pgsql\bin\pg_ctl.exe -D c:\pgsql\data stop
more info