[LU-18938] lu object free eats so much time

• Type: Improvement
• Resolution: Unresolved
• Priority: Critical
• Severity: 3
• Assignee: Alexey Lyashkov
• Reporter: Alexey Lyashkov

Description

While worked on unlink and zfs scalability problems
I found object free eats so much time of unlink, it caused an extra cpu load in the ARC cache flush thread.

16) <...>-2682981 | .... 7.184 us   |     mdd_trans_stop [mdd]();
 16) <...>-2682981 | ....+ 62.367 us  |   } /* mdd_unlink [mdd] */
 16) <...>-2682981 | .... 0.030 us   |   mutex_unlock();
 16) <...>-2682981 | ....+ 43.762 us  |     lu_object_free.isra.36 [obdclass]();
 16) <...>-2682981 | ....+ 46.206 us  |   } /* lu_object_put [obdclass] */
 16) <...>-2682981 | ....! 154.269 us | } /* mdt_reint_unlink [mdt] */

In short evaluation unlink perf increased by 10%-20% by moving object free into separate thread. ZFS have benefits from this change also.

Comments

[Gerrit Updater]

"Alexey Lyashkov <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/58910
Subject: LU-18938 obdclass: delay an object free
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: d2ec441d7a71a816023dc5639d645da37df51176