linux-kernel - Re: [PATCHv2 0/3] zsmalloc: small compaction improvements

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Date:   Wed, 5 Jul 2023 22:28:52 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCHv2 0/3] zsmalloc: small compaction improvements

On (23/06/24 14:12), Sergey Senozhatsky wrote:
> Hi,
> 	A tiny series that can reduce the number of
> find_alloced_obj() invocations (which perform a linear
> scan of sub-page) during compaction. Inspired by Alexey
> Romanov's findings.
> 
> v2:
> -- picked up a patch from Minchan
> 
> Minchan Kim (1):
>   zsmalloc: remove zs_compact_control
> 
> Sergey Senozhatsky (2):
>   zsmalloc: do not scan for allocated objects in empty zspage
>   zsmalloc: move migration destination zspage inuse check

Just for the record,

A synthetic zsmalloc fragmentation+compaction test (100% reproducible)

           num find_tagged_obj() calls     num iterations in find_tagged_obj()

base                 545699                              812899
patch #1             460701                              691821
patch #2             422372                              651372

// lower is better


patch #1 is "zsmalloc: do not scan for allocated objects in empty zspage"
patch #2 is "zsmalloc: move migration destination zspage inuse check"