linux-ext4 - Locality of extent status tree traversal

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Message-ID: <CALe4XzYNBKhtcYvcuME0A29LvPuZEuirD3DLtHnffObRCUU8Rg@mail.gmail.com>
Date:   Tue, 7 May 2019 11:12:07 -0500
From:   Probir Roy <proy.cse@...il.com>
To:     linux-ext4@...r.kernel.org
Subject: Locality of extent status tree traversal

Hi,

I am running Phoronix-fio benchmark on Linux kernel 4.18.0-rc5. I
observe the same nodes have been traversed on the extent status tree
in "ext4_es_lookup_extent" function when ext4 write begins. What's the
locality signature of "ext4_es_lookup_extent" in general? Is it
possible that same logical block being looked up repeatedly
(Temporal)? Is it possible that co-located logical blocks are searched
by ext4_es_lookup_extent (spatial)?  Or is it totally random?

-- 
Probir Roy