[Gluster-users] Poor performance on a server-class system vs. desktop

[Dmitry Antipov]

On 11/26/20 8:14 PM, Gionatan Danti wrote:

> So I think you simply are CPU limited. I remember doing some tests with loopback RAM disks and finding that Gluster used 100% CPU (ie: full load on an entire core) when doing 4K random writes. Side 
> note: using synchronized (ie: fsync) 4k writes, I only get ~600 IOPs even when running both bricks on the same machine and backing them with RAM disks (in other words, with no network or disk 
> bottleneck).

Thanks, it seems you're right. Running local replica 3 volume on 3x1Gb ramdisks, I'm seeing:

top - 08:44:35 up 1 day, 11:51,  1 user,  load average: 2.34, 1.94, 1.00
Tasks: 237 total,   2 running, 235 sleeping,   0 stopped,   0 zombie
%Cpu(s): 38.7 us, 29.4 sy,  0.0 ni, 23.6 id,  0.0 wa,  0.4 hi,  7.9 si,  0.0 st
MiB Mem :  15889.8 total,   1085.7 free,   1986.3 used,  12817.8 buff/cache
MiB Swap:      0.0 total,      0.0 free,      0.0 used.  12307.3 avail Mem

   PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
63651 root      20   0  664124  41676   9600 R 166.7   0.3   0:24.20 fio
63282 root      20   0 1235336  21484   8768 S 120.4   0.1   2:43.73 glusterfsd
63298 root      20   0 1235368  20512   8856 S 120.0   0.1   2:42.43 glusterfsd
63314 root      20   0 1236392  21396   8684 S 119.8   0.1   2:41.94 glusterfsd

So, 32-core server-class system with a lot of RAM can't perform much faster for an
individual I/O client - it just scales better if there are a lot of clients, right?

Dmitry