Linux 6.12 Released With Real-Time Capabilities, Sched_Ext, More AMD RDNA4 & More

[F.Ultra]

Also I realized something.
I suspect that CPU cache is being polluted by compilation. Basically i run FO4 while compiling firefox. Frame dropped bad. I CTRL Z it. FPS was still bad. I foregrounded process and killed it - frames immediately risen. Now if only there was a CPU cache control for Linux.

while the task is paused it cannot cause any cache issues so I wonder if this could simply be down to low mem situation

[guglovich]

It's bloated so they develop a dangerous BPF. We have to wait for Redox and pray for a sequel to Hurd, where features will be enabled as the user needs them.

[eggy]

With this release there was supposed to be support for hardware in ThinkPad T14s with Qualcomm Snapdragon X Elite SoC, is it there? I can't find it
Some drivers were still missing like USB-C driver.

[TNZfr]

I don't know, but your Thinkpad is not the century choice.

In fact I red that they didn't sell a lot of unit. MS should run after 1 target at a time : today they try to put everyone in their sauron's ring (ie Azure AD), to be the 1st in AI (before rules being set), to migrate everyone on Win11 (with TPM, UEFI Secure Boot even if hardware is not compatible) ...

Since AI is not deterministic, how can we maintain a semblance of control over IT? The question of functional developments arises: how can we develop an AI and its objectives more or less well aligned when we have no control over anything?

[dimko]

while the task is paused it cannot cause any cache issues so I wonder if this could simply be down to low mem situation

Can't be the case, 64 Gig of ram, and ram usage is low.

[F.Ultra]

Can't be the case, 64 Gig of ram, and ram usage is low.

well then it is indeed extremely strange since if the task is really paused it is paused and thus it is not running on the cpu and therefore it cannot pollute the cache at all. Who ever said that computers was easy :-)

[dimko]

well then it is indeed extremely strange since if the task is really paused it is paused and thus it is not running on the cpu and therefore it cannot pollute the cache at all. Who ever said that computers was easy :-)

The question becomes, where does existing compilation cache go? RAM? Something tell me - its not the case. Hence the problem.

[F.Ultra]

The question becomes, where does existing compilation cache go? RAM? Something tell me - its not the case. Hence the problem.

If you pause the execution of the compile with ctrl+z (assuming that the whole compilation was actually paused here and not just some parts of it) then there is no compilation cache, every cache line it occupied would be overwritten by the running application (aka the game). It was already in RAM so what happens is that the copy in cache is replaced.

You cannot cache data that doesn't already exist in RAM, when the CPU wants to read a peace of memory it first have to load a full cache line (64 bytes) from that position of RAM into the cache and only then can the CPU perform calculations on the data. Then when it does writes it overwrites the old position in the cache (if it updated the same data it once loaded) and then later the MMU flushes it from cache to actual RAM.

[dimko]

If you pause the execution of the compile with ctrl+z (assuming that the whole compilation was actually paused here and not just some parts of it) then there is no compilation cache, every cache line it occupied would be overwritten by the running application (aka the game). It was already in RAM so what happens is that the copy in cache is replaced.

You cannot cache data that doesn't already exist in RAM, when the CPU wants to read a peace of memory it first have to load a full cache line (64 bytes) from that position of RAM into the cache and only then can the CPU perform calculations on the data. Then when it does writes it overwrites the old position in the cache (if it updated the same data it once loaded) and then later the MMU flushes it from cache to actual RAM.

Thanks for interesting perspective.
Can't help but wonder why do I have a performance drop by using ctrl-z. Even though CPU and RAM usage did not change and CPU usage was significantly lower?

[F.Ultra]

Thanks for interesting perspective.
Can't help but wonder why do I have a performance drop by using ctrl-z. Even though CPU and RAM usage did not change and CPU usage was significantly lower?

I agree that it is an interesting problem that makes me a bit puzzled. One idea would be to see if ctrl-z really paused all the steps in the build, aka if the compiler or make forked other processes to do various things they are not paused if the parent is paused, aka I would bring up top and see if it really is only the game taking up cpu at that point as the first step.