[pve-devel] [RFC PATCH pve-cluster] fix #5728: pmxcfs: allow bigger writes than 4k for fuse

[Dominik Csapak]

On 9/23/24 14:00, Friedrich Weber wrote:
> On 23/09/2024 11:17, Dominik Csapak wrote:
>> [...]
>> so i did some benchmarks (mostly disk writes) and wrote the short script
>> below
>> (maybe we can reuse that?)
>>
>> ----8<----
>> use strict;
>> use warnings;
>>
>> use PVE::Tools;
>>
>> my $size = shift;
>>
>> sub get_bytes_written {
>>          my $fh = IO::File->new("/proc/diskstats", "r");
>>          die if !$fh;
>>          my $bytes = undef;
>>          while (defined(my $line = <$fh>)) {
>>                  if ($line =~ m/sdb/) {
>>                          my @fields = split(/\s+/, $line);
>>                          $bytes = $fields[10] * 512;
>>                  }
>>          }
>>          return $bytes;
>> }
>>
>> sub test_write {
>>          my ($k) = @_;
>>          system("rm /etc/pve/testfile");
>>          my $data = "a"x($k*1024);
>>          system("sync; echo -n 3> /proc/sys/vm/drop_caches");
> 
> I'm not sure this actually drops the caches: Without the space between
> `3` and `>` I think this redirects fd 3 to that file (so doesn't
> actually write the `3`)? I didn't run the script though, so not sure if
> it makes any difference for the results.

ah yeah, i noticed, but forgot to answer here. i fixed it here locally and
rerun the tests but had the same results (+- a bit of variation)