Oh, Hey! First time posting something on the Fedora Forums. I am currently using two pcs. A desktop with GNOME, and a All-In-One with KDE.
Gnome Desktop
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 2.9G 36M 9M 9.7M 4 [SWAP]
KDE All-IN-ONE
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 3.6G 4K 74B 12K 4 [SWAP]
I really have noticed a difference on ram usage since switching to Fedora. I was a pretty frequent distro hopper but I have actually am thinking of sticking with Fedora.
I do not understand this output. Data is more than twice the size of total, so how does this get interpreted with the individual fields. At first glance it seems disksize and total should really be the only items of real concern, then the larger data item is a glaring discrepancy that I can’t seem to interpret. BTW, this is on a system with 32G RAM.
DISKSIZE is just a limit — it’s not actively being used. DATA is the raw amount of uncompressed data in swap, and COMPR is the compressed size. TOTAL is that plus overhead. From zramctl --help
Available output columns:
NAME zram device name
DISKSIZE limit on the uncompressed amount of data
DATA uncompressed size of stored data
COMPR compressed size of stored data
ALGORITHM the selected compression algorithm
STREAMS number of concurrent compress operations
ZERO-PAGES empty pages with no allocated memory
TOTAL all memory including allocator fragmentation and metadata overhead
MEM-LIMIT memory limit used to store compressed data
MEM-USED memory zram have been consumed to store compressed data
MIGRATED number of objects migrated by compaction
MOUNTPOINT where the device is mounted
$ zramctl
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 4G 234.5M 85.9M 88.7M 12 [SWAP]
So if I am understanding this right then total is the compressed + overhead. Data is then the total uncompressed size of all that is in swap. Yet that line in the help says “all memory” + overhead. Seems a bit conflicting since in my experience total would be ALL and here data seems to be ALL and total is a fraction of that.
DATA is “how much would be consumed if this had not been compressed”. It is not included in TOTAL because it isn’t actually taking up that amount of memory. It is taking COMPR amount of memory.
I agree that it is a little confusing for TOTAL to mean “total memory actually used” rather than “all numbers added together”, but the latter wouldn’t be a useful number in any way while the former is.
Pragmatically, the two numbers you want to compare are DATA and TOTAL. The difference between the two is memory made free by compression.
Thanks @tjdoyle@mattdm
I tested it on the f33 sever and the test f34 server, and I confirmed the normal operation through the above configuration. It works well. Have a nice day!
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 3.7G 3.2G 1.8G 1.8G 4 [SWAP]
This is a desktop computer. I often experience Firefox tabs crashing when running resource-intensive applications such as a rsync transfer or Virtualbox.
After you have been running for a long time and have lots of browser tabs open and other apps running
I’ll fire up VM later today and compare the results… relatively low memory-usage at the time.
A bit more digging, as the numbers I quoted above look too good to be true - as indeed they are on further investigation.
I have over 30 firefox tabs open currently (deliberately!) and zram shows:
/sbin/zramctl
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 3.8G 380.2M 112M 117.6M 4 [SWAP]
But I also have an ordinary swap, as follows:
swapon
NAME TYPE SIZE USED PRIO
/dev/dm-0 partition 7.7G 402.1M -2
/dev/zram0 partition 3.8G 386M 100
Not sure whether all F33’s have an ordinary swap, or just upgrades from previous Fedora versions. However, just looking at zramctl isn’t going to give a complete picture unless you know whether there’s an ordinary swap.
I have SSD, so ordinary swap is going to be pretty fast anyway - and without knowing how zram decides when to start using the ordinary swap, it’s difficult to gauge the effectiveness of zram.
Hi, Since using Fedora 33 (Silverblue) I’m experiencing Firefox tabs that keep crashing after some time. I maybe have around 40 tabs open. Chromium doesn’t suffer from this but feels “slowish”
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 3.8G 3.5G 951.7M 997.4M 8 [SWAP]
NAME ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram0 lzo-rle 7.5G 1.7M 484.5K 904K 8 [SWAP]
I’ve noticed that even with virtual machines opened (including windows 10) along with a bunch of browser tabs and VSCode RAM utilization never goes above 60%.
This has killed performance on my Fedora 33 Xeon box with 16G of RAM. I am annoyed that I had to go looking for this, that it didn’t show up in fstab, that swapoff -a didn’t stop swap from being reset again and again.
If you had read the documentation, even online, you could have found that zram swap would be stopped by a simple “touch /etc/systemd/zram-generator.conf” command which would have disabled the creation of zram swap at startup.
You could have even seen how to tailor it to work better for your system by “man zram-generator.conf”.
Fedora 33 had a default size of 4GB for zram and Fedora 34 upped that to 8GB but it is easy to change the defaults to whatever works for you. Fedora 33 & 34 also do not create a swap partition/file by default since they use the zram.
Hmmm, I’m curious about that. In what way is it harming your performance? When not in use, it really shouldn’t have much impact. Do you have some numbers?
