Hi,
I've been trying out the 'Free Trail' of Windows Azure, to see if its something I can use.
I have a Virtual Server set up, only a 'Extra Small' one though as a test.
I have Apache2 and PHP 5.3.8 setup on it.
I seem to be having some kind of performance issue.
I noticed that quite regularly, while in my bash shell, that the cursor would freeze for a few seconds, and I couldnt type anything, after a few seconds it would continue (buffering what it didnt do).
I specifically noticed it in 'vi' quite a bit.
At first, I put it down to my ISP could have been having problems.
But, I've just looked into it, and it seems to be a problem on the server side.
It seems that my server has a problem with the system call fsync() and quite often a call to fsync() is taking upto 5 seconds.
I used strace to trace a 'vi' session, and everytime my keyboard stopped working, the strace would show it was the fsync waiting.
I know I'm on the extra small service, but nothing is running on the server and I really dont think that fsync() should be behaving in this way.
I'm not sure what to do though, because I cant get technical help from MS while on the 'free' subscription, but if this is a problem then I dont really want to be paying for a subscription when this is happening.
I wrote a script to do continual fsync(), one every 10th second, and monitor their speed. I get about 50-150 per hour that are over 1 second, and up to 5 seconds.
I've worked on many systems before, and I've been involved in lots of performance issues, but I've never seen fsync() just take so long like this.
I noticed it because when I 'save' in vi, it does fsyncs, and it does one between deleting the current file, and then copying the temp 'swp' file it has been editing, back to the real file. So if I press save, and then go to my web page and refresh the page I'm edditing too quickly I get a 404 error, as vi is still in the middle of 'saving' still because its waiting for the fsync()
Any help or ideas would be appreciated.
Thanks,
Rob Donovan.