Re: [pve-devel] [PATCH pve-manager] api: ceph: improve reporting of ceph OSD memory usage

[Aaron Lauterer <a.lauterer@proxmox.com>]

one small nitL: if the OSD is powered off, we now send null for the meminfo. 
Maybe set it explicitly to 0 to not change the behavior?

but overall:

Tested-By: Aaron Lauterer <a.lauterer@proxmox.com>

On 8/16/23 16:34, Stefan Hanreich wrote:
> Currently we are using the MemoryCurrent property of the OSD service
> to determine the used memory of a Ceph OSD. This includes, among other
> things, the memory used by buffers [1]. Since BlueFS uses buffered
> I/O, this can lead to extremely high values shown in the UI.
> 
> Instead we are now reading the PSS value from the proc filesystem,
> which should more accurately reflect the amount of memory currently
> used by the Ceph OSD.
> 
> We decided on PSS over RSS, since this should give a better idea of
> used memory - particularly when using a large amount of OSDs on one
> host, since the OSDs share some of the pages.
> 
> [1] https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt
> 
> Signed-off-by: Stefan Hanreich <s.hanreich@proxmox.com>
> ---
>   PVE/API2/Ceph/OSD.pm | 19 ++++++++++++++-----
>   1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/PVE/API2/Ceph/OSD.pm b/PVE/API2/Ceph/OSD.pm
> index ded359904..5f7718b0a 100644
> --- a/PVE/API2/Ceph/OSD.pm
> +++ b/PVE/API2/Ceph/OSD.pm
> @@ -687,13 +687,10 @@ __PACKAGE__->register_method ({
>   
>   	my $raw = '';
>   	my $pid;
> -	my $memory;
>   	my $parser = sub {
>   	    my $line = shift;
>   	    if ($line =~ m/^MainPID=([0-9]*)$/) {
>   		$pid = $1;
> -	    } elsif ($line =~ m/^MemoryCurrent=([0-9]*|\[not set\])$/) {
> -		$memory = $1 eq "[not set]" ? 0 : $1;

here we lose setting the value explicitly to 0 if not available

>   	    }
>   	};
>   
> @@ -702,12 +699,24 @@ __PACKAGE__->register_method ({
>   	    'show',
>   	    "ceph-osd\@${osdid}.service",
>   	    '--property',
> -	    'MainPID,MemoryCurrent',
> +	    'MainPID',
>   	];
>   	run_command($cmd, errmsg => 'fetching OSD PID and memory usage failed', outfunc => $parser);
>   
>   	$pid = defined($pid) ? int($pid) : undef;
> -	$memory = defined($memory) ? int($memory) : undef;
> +
> +	my $memory;
> +	if ($pid && $pid > 0) {
> +	    open (my $SMAPS, '<', "/proc/$pid/smaps_rollup")
> +		or die 'Could not open smaps_rollup for Ceph OSD';
> +
> +	    while (my $line = <$SMAPS>) {
> +		if ($line =~ m/^Pss:\s+([0-9]+) kB$/) {
> +		    $memory = $1 * 1024;
> +		    last;
> +		}
> +	    }
> +	}
>   
>   	my $data = {
>   	    osd => {