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From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: Probir Roy <proy.cse@gmail.com>
Cc: willy@linux.intel.com, kernelnewbies@kernelnewbies.org
Subject: Re: radix_tree_next_chunk: redundant search for next slot in hole
Date: Fri, 03 May 2019 18:38:39 -0400	[thread overview]
Message-ID: <6489.1556923119@turing-police> (raw)
In-Reply-To: <CALe4XzaF3efHzQi0k+gRHXp5ec0kbrtHzo2o_xdk6T5x8vr+-Q@mail.gmail.com>


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On Fri, 03 May 2019 16:03:46 -0500, Probir Roy said:

> While searching for next slot in a hole, it walks through the same
> slots over n over.

How did you determine this?

>           while (++offset < RADIX_TREE_MAP_SIZE) {
>                     void *slot = rcu_dereference_raw(   /* redundant slot walk */
>                             node->slots[offset]);
>                     if (slot)
>                         break;
>                 }

Looks to me like the ++offset will walk through each potential slot once,
and break out if it finds one.

I haven't looked at the code closely, perhaps what you're seeing is repeated
scan/merge/rescan behavior?  Often, compacting a data structure requires
multiple passes.

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  reply	other threads:[~2019-05-03 22:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-03 21:03 radix_tree_next_chunk: redundant search for next slot in hole Probir Roy
2019-05-03 22:38 ` Valdis Klētnieks [this message]
2019-05-04  0:00   ` Probir Roy
2019-05-04  0:56     ` Valdis Klētnieks

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