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> Windows Defender is using 2186 MiB of RAM. I don’t think that’s appropriate. These memory-type debates come up time and time again. Keep in mind I'm a progr

> Windows Defender is using 2186 MiB of RAM. I don’t think that’s appropriate. These memory-type debates come up time and time again. Keep in mind I'm a programmer from the DOS days, note my user name on when this was an important issue. We had to cram every byte. These programs will use idle RAM as they see necessary to be performant. If you aren't using the RAM, why not actually use it for what it's for? Are you under memory pressure? How many GB of RAM do you currently have and how often are you capping it out? Try seeing what happens when you are at your GB RAM cap. "I don't think that's appropriate" is highly subjective and it depends on what it does, and what you are currently doing.

beagle3 5y ago
Where’s the setting where one decides between file system cache, anti-virus, swap space, and other uses? If there was one, it would be fine.
- TameAntelope 5y ago
  Why are you trying to manage it? Let the OS do its thing, it’s really good at memory management.
  - gruez 5y ago
    AFAIK the OS file cache doesn't get counted towards the process's memory usage, so if windows defender is showing up as using 2GB of memory, it really is using 2GB of memory for the app itself.
  - beagle3 5y ago
    I have a DBMS, a browser, and an antivirus - all of which would love to have "free ram" that's not currently in use by other programs in order to speed up its own work. How do I tell the system which of them I prefer (or some rank), instead of letting them fight it out, each of them thinking that they are the process entitled to all the perks of the currently unused memory?
    - EMM_386 5y ago
      > instead of letting them fight it out Nothing is "fighting it out", there are internal heuristics to understand what applications need that RAM. This is an internal OS feature of modern operating systems. If you are not capped out on RAM usage, this point is moot. If you are truly running at the RAM cap, to where the OS is paging out memory to disk and you have contention, you need more RAM.
      - beagle3 5y ago
        Yes, but the context of this discussion was Q:"why is Windows Defender using 2GB of ram!?!?" A:"It only does that if no other process needs the memory". Which works fine only if there is only one distinguished process. My point was that there isn't one distinguished process, and that thus -- as you described -- it should be left to the OS to decide and not to Windows Defender.
    - happymellon 5y ago
      Either they need the memory or they don't. If they feel like they need to store something to save on network costs then they should store it, and the OS will page it if it isn't used often. The AV doesn't need to take "free ram" except when it tries to guess what the OS will do with disk cache. But by putting it in the AV cache it then prevents other software from using the cache. Just use the OS level disk cache.
- omegalulw 5y ago
  He is saying that many programs are written to use "free RAM", ergo unless defender is still using 2GB ram when your PC is at your RAM limit you don't have a problem. Every OS does it, let your OS manage RAM.
  - gruez 5y ago
    >Every OS does it, let your OS manage RAM. Unlike linux[1], windows task manager correctly shows "cached" ram as "free" ram. Therefore it's highly unlikely that the memory usage is from the OS caching mechanism. As for the actual behavior of using free ram, what happens if there are two apps that try to use the same behavior? ie. you have windows defender and a DBMS installed, both of them try to use up all the free ram. In this situation, what makes you think the behavior of "using all the available free RAM" behavior of windows defender wouldn't push out the "using all the available free RAM" behavior of the DMBS", leading to worse performance? [1] https://www.linuxatemyram.com/ https://www.linuxatemyram.com/
    - jcrawfordor 5y ago
      Task Manager does not report memory use by the OS I/O cache, but there's no general way for it to know what portion of process memory is "necessary" versus "nice to have," so many processes have some type of internal caching (web browsers for example!) that they are able to dump but will be included in their reported memory consumption. Windows has several different layers of caching which makes this a bit complicated to generalize about, but that's sort of the point... Task Manager is not clairvoyant, and so if a process has allocated memory other than specifically through an OS caching infrastructure it reports it as memory in use. The OS caching infrastructure is not so general that it covers every need to hold some memory for performance optimization. Windows has an infrastructure to prioritize memory availability by process, and to notify processes when there is physical memory pressure so that they can act accordingly. I'm not sure, but as a first-party component I would assume that Windows Defender uses these appropriately. That said, like most real-time antivirus Defender does feel that it is important to complete real-time protection scans and will sometimes do so at the cost of performance. The logic here is that it is important to complete these scans even under conditions of resource pressure, otherwise malware could just do things like cause high system load before downloading a second stage in order to avoid Defender completing a real-time scan. Unfortunately this does sometimes cause headaches, for example I saw a situation recently where someone ran a tool that opened a huge number of media files on a NAS in order to read their metadata. This resulted in Defender queuing up a real-time scan of probably over a TB over the network since it saw all of these 10GB+ files being touched, with a definite negative impact on performance. I still wouldn't give "exclude network mounts" as general advice as some people do, but that's an example of sort of a pathological case for real-time scanning where you probably want to exclude it.
fuzzy2 5y ago
Sure maybe the memory is freed (or paged out) as pressure rises. The former is however not guaranteed in any way and requires that Windows Defender (or whatever other application) actively monitor the memory situation, taking appropriate action as it changes. That's something I'd expect a database to do. A virus scanner? Not so much.
- swasheck 5y ago
  every new dotnet package, powershell module, go module, container image, etc that i pull and want to start using results in about 10 minutes of complete system unavailability due to defender going off the rails with ram and cpu consumption. it used to be i’d have to wait for the compiler to build, now i have to wait for defender to defend.
  - smt88 5y ago
    Interesting. I haven't had this experience at all. Are you using non-standard settings? I think you can exclude certain directories from Defender scanning too.
    - swasheck 5y ago
      i’m using the corporate gpo-enforced settings. i’ll try to override them tomorrow.
csmpltn 5y ago
> "Are you under memory pressure? How many GB of RAM do you currently have and how often are you capping it out? Try seeing what happens when you are at your GB RAM cap." Where's the explicit code in Defender which ensures it only does its' thing if the system isn't under heavy load? Also, you do realize that if every program followed this pattern - it would cease to work?

beagle3 5y ago

Where’s the setting where one decides between file system cache, anti-virus, swap space, and other uses? If there was one, it would be fine.

TameAntelope 5y ago
Why are you trying to manage it? Let the OS do its thing, it’s really good at memory management.
- gruez 5y ago
  AFAIK the OS file cache doesn't get counted towards the process's memory usage, so if windows defender is showing up as using 2GB of memory, it really is using 2GB of memory for the app itself.
- beagle3 5y ago
  I have a DBMS, a browser, and an antivirus - all of which would love to have "free ram" that's not currently in use by other programs in order to speed up its own work. How do I tell the system which of them I prefer (or some rank), instead of letting them fight it out, each of them thinking that they are the process entitled to all the perks of the currently unused memory?
  - EMM_386 5y ago
    > instead of letting them fight it out Nothing is "fighting it out", there are internal heuristics to understand what applications need that RAM. This is an internal OS feature of modern operating systems. If you are not capped out on RAM usage, this point is moot. If you are truly running at the RAM cap, to where the OS is paging out memory to disk and you have contention, you need more RAM.
    - beagle3 5y ago
      Yes, but the context of this discussion was Q:"why is Windows Defender using 2GB of ram!?!?" A:"It only does that if no other process needs the memory". Which works fine only if there is only one distinguished process. My point was that there isn't one distinguished process, and that thus -- as you described -- it should be left to the OS to decide and not to Windows Defender.
  - happymellon 5y ago
    Either they need the memory or they don't. If they feel like they need to store something to save on network costs then they should store it, and the OS will page it if it isn't used often. The AV doesn't need to take "free ram" except when it tries to guess what the OS will do with disk cache. But by putting it in the AV cache it then prevents other software from using the cache. Just use the OS level disk cache.
omegalulw 5y ago
He is saying that many programs are written to use "free RAM", ergo unless defender is still using 2GB ram when your PC is at your RAM limit you don't have a problem. Every OS does it, let your OS manage RAM.
- gruez 5y ago
  >Every OS does it, let your OS manage RAM. Unlike linux[1], windows task manager correctly shows "cached" ram as "free" ram. Therefore it's highly unlikely that the memory usage is from the OS caching mechanism. As for the actual behavior of using free ram, what happens if there are two apps that try to use the same behavior? ie. you have windows defender and a DBMS installed, both of them try to use up all the free ram. In this situation, what makes you think the behavior of "using all the available free RAM" behavior of windows defender wouldn't push out the "using all the available free RAM" behavior of the DMBS", leading to worse performance? [1] https://www.linuxatemyram.com/ https://www.linuxatemyram.com/
  - jcrawfordor 5y ago
    Task Manager does not report memory use by the OS I/O cache, but there's no general way for it to know what portion of process memory is "necessary" versus "nice to have," so many processes have some type of internal caching (web browsers for example!) that they are able to dump but will be included in their reported memory consumption. Windows has several different layers of caching which makes this a bit complicated to generalize about, but that's sort of the point... Task Manager is not clairvoyant, and so if a process has allocated memory other than specifically through an OS caching infrastructure it reports it as memory in use. The OS caching infrastructure is not so general that it covers every need to hold some memory for performance optimization. Windows has an infrastructure to prioritize memory availability by process, and to notify processes when there is physical memory pressure so that they can act accordingly. I'm not sure, but as a first-party component I would assume that Windows Defender uses these appropriately. That said, like most real-time antivirus Defender does feel that it is important to complete real-time protection scans and will sometimes do so at the cost of performance. The logic here is that it is important to complete these scans even under conditions of resource pressure, otherwise malware could just do things like cause high system load before downloading a second stage in order to avoid Defender completing a real-time scan. Unfortunately this does sometimes cause headaches, for example I saw a situation recently where someone ran a tool that opened a huge number of media files on a NAS in order to read their metadata. This resulted in Defender queuing up a real-time scan of probably over a TB over the network since it saw all of these 10GB+ files being touched, with a definite negative impact on performance. I still wouldn't give "exclude network mounts" as general advice as some people do, but that's an example of sort of a pathological case for real-time scanning where you probably want to exclude it.

fuzzy2 5y ago

Sure maybe the memory is freed (or paged out) as pressure rises. The former is however not guaranteed in any way and requires that Windows Defender (or whatever other application) actively monitor the memory situation, taking appropriate action as it changes. That's something I'd expect a database to do. A virus scanner? Not so much.

swasheck 5y ago
every new dotnet package, powershell module, go module, container image, etc that i pull and want to start using results in about 10 minutes of complete system unavailability due to defender going off the rails with ram and cpu consumption. it used to be i’d have to wait for the compiler to build, now i have to wait for defender to defend.
- smt88 5y ago
  Interesting. I haven't had this experience at all. Are you using non-standard settings? I think you can exclude certain directories from Defender scanning too.
  - swasheck 5y ago
    i’m using the corporate gpo-enforced settings. i’ll try to override them tomorrow.

csmpltn 5y ago

> "Are you under memory pressure? How many GB of RAM do you currently have and how often are you capping it out? Try seeing what happens when you are at your GB RAM cap." Where's the explicit code in Defender which ensures it only does its' thing if the system isn't under heavy load? Also, you do realize that if every program followed this pattern - it would cease to work?