Another Caveat, To GPU-Computing

I had written in previous postings, that I had replaced the ‘Nouveau’ graphics-drivers, that are open-source, with proprietary ‘nVidia’ drivers, that offer more capabilities, on the computer which I name ‘Plato’. In this previous posting, I described a bug that had developed between these recent graphics-drivers, and ‘xscreensaver’.

Well there is more, that can go wrong between the CPU and the GPU of a computer, if the computer is operating a considerable GPU.

When applications set up ‘rendering pipelines’ – aka contexts – they are loading data-structures as well as register-values, onto the graphics card and onto its graphics memory. Well, if the application, that would according to older standards only have resided in system memory, either crashes, or gets forcibly closed using a ‘kill -9′ instruction, then the kernel and the graphics driver will fail to clean up, whatever data-structures it had set up on the graphics card.

The ideal behavior would be, that if an application crashes, the kernel not only clean up whatever resources it was using in system memory, and within the O/S, but also, belonging to graphics memory. And for all I know, the programmers of the open-source drivers under Linux may have made this a top priority. But apparently, nVidia did not.

And so a scenario which can take place, is that the user needs to kill a hung application that was making heavy use of the graphics card, and that afterward, the state of the graphics card is corrupted, so that for example, ‘OpenCL‘ kernels will no longer run on it correctly.

Continue reading Another Caveat, To GPU-Computing

Upgrade, Downtime

Today, the computers I name ‘Phoenix’ and ‘Klystron’ received major updates to their core ‘libgcc’ and ‘libstdc++’ libraries, as part of a combination of 25 actually-updated packages. Even though this did not upgrade the (Linux) Debian version of either O/S, which is still ‘8.10’ , This type of an upgrade requires a reboot. So I rebooted.

But, The PC which I name ‘Phoenix’ is also my Web-server. Therefore, there is no way for my blog or site to be visible to the Internet, during a reboot. My blog was offline from 20h15 until 20h25.

I apologize for any inconvenience this might have been to my readers.

Dirk

 

My Pixel C Tablet Ran Out Of Power Last Night.

I own a Google Pixel C tablet, that runs Android 8.1.0 . As is customary for me, I leave it In Standby each night, which means that it’s still drawing some small amount of current from its battery.

Usually, I’d inspect the tablet before going to bed each night, to verify that it will still have enough juice in its battery, to sleep through the night. But somehow, last night, I just failed to verify this, and assumed that the tablet was okay to sleep through the night.

Also, I slept-in this morning. Well as I was sleeping in, the tablet made a few notification sounds which I’d never heard from it before, and the fact that it was doing so did not alarm me in my sleep.

So this morning, when I tried to reboot the tablet, it would proceed partially into the boot process, and then just play its notification sound, and shut off again. So what I needed to do was leave it plugged in for two hours, and then try rebooting it again. Which worked!

But there was just a possible scenario in my mind, of what could have gone wrong last night, and what could potentially have bricked the tablet.

Continue reading My Pixel C Tablet Ran Out Of Power Last Night.

System Update Today, Downtime

I take the unusual measure, of hosting my Web-site, and therefore also this blog, on a PC running at home. The PC I use is the Debian / Jessie (Linux) computer I name ‘Phoenix’.

This morning, I installed a major set of updates on this computer, which included 137 packages, and doing so, brought it from Debian version 8.9 to version 8.10 .

But, because this PC is also my Web-server, the required reboot also meant, that the site was offline from about 10h20 until about 10h30.

I apologize for any inconvenience.

BTW, ‘Phoenix’ had been Up, for 62 straight days.

It’s too early really to tell, whether this large an update has affected reliability adversely, but they usually do not. So for now, I’m counting this as a successful update.

Dirk