[LU-3451] Editor closes file very slow because of fsync()

• Type: Bug
• Resolution: Not a Bug
• Priority: Major
• Affects Version/s: Lustre 1.8.8
• Labels: ldiskfs
• Environment: Kernel: 2.6.32-220.el6.x86_64; Lustre: 1.8.8
• Severity: 3
• Assignee: Peter Jones
• Reporter: Li Xi (Inactive)

Description

When edit a file by emacs or vim and save it, it takes a couple of seconds to close it. This problen is not limited to a specific file, client or OST, and can be reproduced easily at any file or any client. It occurs with root user. There is no error recorded on MDS/OSS/client syslog for it.

We traced the process and got Lustre log. According to the strace, it takes seconds while fsync(). And according to Lustre log of client, mdc_sync() waits for seconds until it recieves the reply. But the log on Lustre MDS does not contain any message about mds_sync().

We do not find any problem of other metadata operations like file creation or direcotry creation. The simple test 'fsync.c' opens, writes to and then fsync a file but it can not reproduce the problem.