[pve-devel] ceph performance

[Alexandre DERUMIER]

>>I'm not sure, I known that it can impact performance on osd, but not sure about the client. 

I Confirm, it's only for the osd and data flushes

https://github.com/ceph/ceph/commit/07498d66233f388807a458554640cb77424114c0
(But If One day we want to support ceph on promox host, I think We'll need to backport libc6)



+#ifdef HAVE_SYS_SYNCFS
 	 1475	
+  if (syncfs(fd) == 0) {
 	 1476	
+    dout(0) << "mount syncfs(2) syscall fully supported (by glibc and kernel)" << dendl;
 	 1477	
+  } else {
 	 1478	
+    dout(0) << "mount syncfs(2) syscall supported by glibc BUT NOT the kernel" << dendl;
 	 1479	
+  } else
 	 1480	
+#endif
 	 1481	
+  {
 	 1482	
+    if (btrfs) {
 	 1483	
+      dout(0) << "mount syncfs(2) syscall not support by glibc, but the btrfs SYNC ioctl will suffice" << dendl;
 	 1484	
+    } else if (m_filestore_fsync_flushes_journal_data) {
 	 1485	
+      dout(0) << "mount syncfs(2) syscall not support by glibc, but 'filestore fsync flushes journal data = true', so fsync will suffice." << dendl;
 	 1486	
+    } else {
 	 1487	
+      dout(0) << "mount syncfs(2) syscall not support by glibc; must use sync(2)." << dendl;
 	 1488	
+      dout(0) << "mount WARNING: multiple ceph-osd daemons on the same host will be slow" << dendl;
 	 1489	
+    }
 	 1490	
+  }
 	 1491	
+
 	 1492	
+




	

Alexandre D e rumier 

Ingénieur Systèmes et Réseaux 


Fixe : 03 20 68 88 85 

Fax : 03 20 68 90 88 


45 Bvd du Général Leclerc 59100 Roubaix 
12 rue Marivaux 75002 Paris 


----- Mail original ----- 

De: "Alexandre DERUMIER" <aderumier at odiso.com> 
À: "Dietmar Maurer" <dietmar at proxmox.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Lundi 5 Novembre 2012 06:05:57 
Objet: Re: [pve-devel] ceph performance 

>>Maybe that is the reason for the bad performance? 

I'm not sure, I known that it can impact performance on osd, but not sure about the client. 

I'll tell te question on the mailing list. 
----- Mail original ----- 

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: pve-devel at pve.proxmox.com 
Envoyé: Dimanche 4 Novembre 2012 16:20:13 
Objet: [pve-devel] ceph performance 



I guess we do not have syncfs support in our libc: 

http://ceph.com/docs/master/install/os-recommendations/ 

But the RHEL6.3 kernel includes that syscall. Can we compile ceph using the syscall directly? 

Maybe that is the reason for the bad performance? 

- Dietmar 
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