Limit cpu usage when client is updating

Hello Magnus,

AFAIK - no. very sensitive - what kind of issues do you experience?

Christian

Hi,

It's a bit theoretical, there hasn't been any issues besides that they can spot the cpu spike while sophos is updating. But their fear is that this could happen at a time where the markets are very busy and their server is already at a very high cpu load. We are in the fund management sector.

If it's correct that sophos will take all cpu it can from two cores that means it could potentially take 25% of the servers (8 cores) total cpu.

Please correct me if my assumptions are wrong!

Thanks,

Magnus

Hello Magnus,

some background (from the little - that might even be incorrect - knowledge I have).
The AutoUpdate service (ALsvc.exe) starts ALUpdate.exe (with AFAIK  normal priority). ALUpdate checks the catalogs first, comparing its cached version with those on the CID. If there's a difference (every few hours when there are definition updates, or when there's a major update) it "synchronizes" cache and CID and recalculates (I think that's what it does) the checksums for the product's files - in case of the savxp component some 800 files almost 300MB. savservice will kick in when the files are accessed. Afterwards the product is "installed", in case of a minor update some checks are performed and savservice.exe is told to reload its data. all cpu it can - yes, but can not in the sense that either process is trying to get all there is, they are just competing for resources at the normal priority level.

I don't have numbers for CPU consumption, only estimates and wall-clock times on my 4-core i7 2.8GHz from a simple test I've just performed: The synchronization takes 3-4 seconds, savservice reloading its data another 10 or so. It doesn't look like ALUpdate uses more than one core, at no point it used the equivalent of one core. Largest spike is during synchronization when savservice is also active. None of the cores got anywhere near 100%, the total stayed well below 50% - this on a more or less idle system.

Of course - very simplified - if you have just two processes that each use almost 50% of total CPU and you start another one competing at the same priority that can potentially also take 50% each would then get about 30%. In practice it's much more complex.

Christian 

Hello Magnus,

some background (from the little - that might even be incorrect - knowledge I have).
The AutoUpdate service (ALsvc.exe) starts ALUpdate.exe (with AFAIK  normal priority). ALUpdate checks the catalogs first, comparing its cached version with those on the CID. If there's a difference (every few hours when there are definition updates, or when there's a major update) it "synchronizes" cache and CID and recalculates (I think that's what it does) the checksums for the product's files - in case of the savxp component some 800 files almost 300MB. savservice will kick in when the files are accessed. Afterwards the product is "installed", in case of a minor update some checks are performed and savservice.exe is told to reload its data. all cpu it can - yes, but can not in the sense that either process is trying to get all there is, they are just competing for resources at the normal priority level.

I don't have numbers for CPU consumption, only estimates and wall-clock times on my 4-core i7 2.8GHz from a simple test I've just performed: The synchronization takes 3-4 seconds, savservice reloading its data another 10 or so. It doesn't look like ALUpdate uses more than one core, at no point it used the equivalent of one core. Largest spike is during synchronization when savservice is also active. None of the cores got anywhere near 100%, the total stayed well below 50% - this on a more or less idle system.

Of course - very simplified - if you have just two processes that each use almost 50% of total CPU and you start another one competing at the same priority that can potentially also take 50% each would then get about 30%. In practice it's much more complex.

Christian