Do you use more memory to reduce the swap file size in Linux?
27 Apr 2022 16:18:08 UTC
Topic 227461
(moderation:
I have noticed in Einstein that there is what I consider to be an excessive amount of "Peak Swap Size", as in this file of mine:
Task 1277396184
|
Name: LATeah3012L07_748.0_0_0.0_30493080_0
Workunit ID: 632849162
Created: 20 Apr 2022 21:33:02 UTC
Sent: 20 Apr 2022 22:30:53 UTC
Report deadline: 4 May 2022 22:30:53 UTC
Received: 21 Apr 2022 0:00:27 UTC
Server state: Over
Outcome: Success
Client state: Done
Exit status: 0 (0x00000000)
Computer: 12895648
Run time (sec): 122.80
CPU time (sec): 120.74
Peak working set size (MB): 228.75
Peak swap size (MB): 6127.01
Peak disk usage (MB): 0.02
Validation state: Valid
Granted credit: 3,465
Application: Gamma-ray pulsar binary search #1 on GPUs v1.28 (FGRPopencl2Pup-nvidia) x86_64-pc-linux-gnu
When checking my own swap file size in Linux Ubuntu 20.04.3 LTS, I get this:
george@GWG-PC3:~$ free -h
I'm wondering if I were to increase my memory would I be reducing the amount of "swapping" back and forth of the files so that they can be completed as Valid faster.
As it is now, I'm running a 5950X using a SAMSUNG 970 Plus SSD 1TB M.2 NVMe as my boot drive and for BOINC with 32GB of DDR4-3600 CL14 DRAM, so I think it is fairly fast.
Can I make it run faster? |
George
Proud member of the Old Farts Association
Yes you can increase your
)
Yes you can increase your swap size. But it won't make the tasks run any faster.
You can increase your memory but it won't make tasks run much faster.
I have all the Ryzens on 32GB same as you. I have a swap file of 6GB on this daily driver and I still see swap activity.
Only on the Epyc hosts with 128GB do they show no activity or usage of the default 2GB swap file.
Keith Myers wrote: Yes you
)
So even if I were to increase my memory to 128GB, my system would still be "swapping" files on my SSD?
Frankly, I am having a bit of trouble seeing the benefit of increasing the swap file size. That just gives it more room to swap out files from memory and I want to have less swapping activity.
Proud member of the Old Farts Association
if you have enough system
)
if you have enough system memory, and you don't think you'll ever be in a situation of running out, you can delete the swap entirely.
_________________________________________________________________________
When checking my own swap
)
When checking my own swap file size in Linux Ubuntu 20.04.3 LTS, I get this:
george@GWG-PC3:~$ free -h
total used free shared buff/cache available
Mem: 31Gi 4.7Gi 5.9Gi 55Mi 20Gi 26Gi
Swap: 2.0Gi 363Mi 1.6Gi
george@GWG-PC3:~$
What puzzles me is my memory is showing that I have 32/31GB total, and I'm using just 4.7GB with 5.9GB "free".
Could you describe to me what is the "shared", "buff/cache" and "available" memory listed? The numbers just don't add up.
And if I don't kill the swap file altogether when adding more ram, will I just use the swap file because it's there?
Proud member of the Old Farts Association
Buffers Are used by
)
Buffers
Are used by programs with active I/O operations, i.e. data waiting to be written to disk
Cache
Is the result of completed I/O operations, i.e. buffers that have been flushed or data read from disk to satisfy a request.
As I mentioned in my previous post, with 128GB of memory I haven't touched the swap file once. I could just as easily remove it entirely. Ubuntu installs a 2GB swap file by default whether there is little or a lot of memory.
The only reason I increased mine is because the daily driver was occasionally using more than the 2GB because of all the stuff running on it. The Boinctasks history and the Gridcoin wallet putting the extra demand on the memory pool. This host is the only one I needed to increase the swap file size.
Ian&Steve C. wrote: if you
)
In the latest distros and kernels, they improved the oomd driver so that the kernel does not get into a panic situation when you run out of memory. Helpful for 1GB Rpi's and such. Plus, it acts smarter and will kill off unnecessary processes to relieve the memory pressure. All to keep the kernel happy and the host running.
George, I don't know why you are worrying so much. Linux is very smart about memory management.
With the system installed on a M.2 SSD, any swap activity, if needed at all, is going to be very fast and have very minimal impact on the rest of the system processes.
Ian&Steve C. wrote: if you
)
Does that only apply to Linux or also Windows? Is there a benefit to deleting it?
Quoting Keith: "George, I
)
Quoting Keith:
"George, I don't know why you are worrying so much. Linux is very smart about memory management.
With the system installed on a M.2 SSD, any swap activity, if needed at all, is going to be very fast and have very minimal impact on the rest of the system processes."
I am not "worrying so much", I was just wondering (aloud?) about the cache and swap file size and trying to see if it made any difference in speed for Einstein with the CPU stage of GPU usage. I spend about 20/30 secs in CPU mode before I get another GPU task for my 3080.
Proud member of the Old Farts Association
Boca Raton Community HS
)
you can do it on Windows too. Windows calls it the pagefile. you can select an option in the system settings under virtual memory to remove it.
no performance benefit in doing so. but it'll reclaim some disk space on your OS drive.
_________________________________________________________________________
Boca Raton Community HS
)
No. No benefit. OS's are smart in their memory management. Best to let them do their normal stuff as designed by default for almost all use cases.