linux-kernel - Re: [PATCH -next v6 0/2] Make memory reclamation measurable

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Date: Wed, 24 Jan 2024 10:41:48 +0800
From: Bixuan Cui <cuibixuan@...o.com>
To: akpm@...ux-foundation.org, rostedt@...dmis.org, mhiramat@...nel.org,
 mathieu.desnoyers@...icios.com
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 linux-mm@...ck.org, opensource.kernel@...o.com
Subject: Re: [PATCH -next v6 0/2] Make memory reclamation measurable

ping~

在 2024/1/5 9:36, Bixuan Cui 写道:
> When the system memory is low, kswapd reclaims the memory. The key steps
> of memory reclamation include
> 1.shrink_lruvec
>    * shrink_active_list, moves folios from the active LRU to the inactive LRU
>    * shrink_inactive_list, shrink lru from inactive LRU list
> 2.shrink_slab
>    * shrinker->count_objects(), calculates the freeable memory
>    * shrinker->scan_objects(), reclaims the slab memory
> 
> The existing tracers in the vmscan are as follows:
> 
> --do_try_to_free_pages
> --shrink_zones
> --trace_mm_vmscan_node_reclaim_begin (tracer)
> --shrink_node
> --shrink_node_memcgs
>    --trace_mm_vmscan_memcg_shrink_begin (tracer)
>    --shrink_lruvec
>      --shrink_list
>        --shrink_active_list
> 	  --trace_mm_vmscan_lru_shrink_active (tracer)
>        --shrink_inactive_list
> 	  --trace_mm_vmscan_lru_shrink_inactive (tracer)
>      --shrink_active_list
>    --shrink_slab
>      --do_shrink_slab
>      --shrinker->count_objects()
>      --trace_mm_shrink_slab_start (tracer)
>      --shrinker->scan_objects()
>      --trace_mm_shrink_slab_end (tracer)
>    --trace_mm_vmscan_memcg_shrink_end (tracer)
> --trace_mm_vmscan_node_reclaim_end (tracer)
> 
> If we get the duration and quantity of shrink lru and slab,
> then we can measure the memory recycling, as follows
> 
> Measuring memory reclamation with bpf:
>    LRU FILE:
> 	CPU COMM 	ShrinkActive(us) ShrinkInactive(us)  Reclaim(page)
> 	7   kswapd0	 	26		51		32
> 	7   kswapd0		52		47		13
>    SLAB:
> 	CPU COMM 		OBJ_NAME		Count_Dur(us) Freeable(page) Scan_Dur(us) Reclaim(page)
> 	 1  kswapd0		super_cache_scan.cfi_jt     2		    341		   3225		128
> 	 7  kswapd0		super_cache_scan.cfi_jt     0		    2247	   8524		1024
> 	 7  kswapd0	        super_cache_scan.cfi_jt     2367	    0		   0		0
> 
> For this, add the new tracer to shrink_active_list/shrink_inactive_list
> and shrinker->count_objects().
> 
> Changes:
> v6: * Add Reviewed-by from Steven Rostedt.
> v5: * Use 'DECLARE_EVENT_CLASS(mm_vmscan_lru_shrink_start_template' to
> replace 'RACE_EVENT(mm_vmscan_lru_shrink_inactive/active_start'
>      * Add the explanation for adding new shrink lru events into 'mm: vmscan: add new event to trace shrink lru'
> v4: Add Reviewed-by and Changlog to every patch.
> v3: Swap the positions of 'nid' and 'freeable' to prevent the hole in the trace event.
> v2: Modify trace_mm_vmscan_lru_shrink_inactive() in evict_folios() at the same time to fix build error.
> 
> cuibixuan (2):
>    mm: shrinker: add new event to trace shrink count
>    mm: vmscan: add new event to trace shrink lru
> 
>   include/trace/events/vmscan.h | 80 ++++++++++++++++++++++++++++++++++-
>   mm/shrinker.c                 |  4 ++
>   mm/vmscan.c                   | 11 +++--
>   3 files changed, 90 insertions(+), 5 deletions(-)
>