[LU-32] always keep buffer_head reference on root node of iam_container

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.2.0, Lustre 2.1.4
• Affects Version/s: Lustre 2.0.0
• Assignee: Liang Zhen (Inactive)
• Reporter: Liang Zhen (Inactive)

Description

IAM in ldiskfs-osd will always consume some slots in bh_lru (see: fs/buffer.c), if we keep buffer_head reference on root node, we can save one slot in bh_lru and could be somehow helpful for overall performance, I did some tests, LRU hits increased 5%-10% while creating files if we always keep this reference.

I'm not expert of this, so please post your comment here if it's totally wrong to do this.

Issue Links

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