These kernel parameters influence the flushing of data, and also performance:
vm.dirty_bytes
vm.dirty_background_bytes
Smaller vm.dirty_background_bytes will make the transfer more smooth and the ceph cluster will like that. However, it reduces the chances of merge operations in cache and the ceph cluster will not like that. The tuning is heavily workload dependent. Test with realistic workloads and a reasonably large spectrum of values. I got good results by tuning down vm.dirty_background_bytes just to the point when it reduced client performance of copying large files.
Best regards,
=================
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
________________________________________
From: Sage Meng <lkkey80@xxxxxxxxx>
Sent: 06 November 2020 13:45:53
To: ceph-users@xxxxxxx
Subject: Is there a way to make Cephfs kernel client to write data to ceph osd smoothly with buffer io
Hi All,
Cephfs kernel client is influenced by kernel page cache when we write
data to it, outgoing data will be huge when os starts flush page cache.
So Is there a way to make Cephfs kernel client to write data to ceph osd
smoothly when buffer io is used ?
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