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From: Nitin Gupta <nigupta@nvidia.com>
To: chukaiping <chukaiping@baidu.com>,
	"mcgrof@kernel.org" <mcgrof@kernel.org>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"yzaikin@google.com" <yzaikin@google.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"vbabka@suse.cz" <vbabka@suse.cz>,
	"bhe@redhat.com" <bhe@redhat.com>,
	"khalid.aziz@oracle.com" <khalid.aziz@oracle.com>,
	"iamjoonsoo.kim@lge.com" <iamjoonsoo.kim@lge.com>,
	"mateusznosek0@gmail.com" <mateusznosek0@gmail.com>,
	"sh_def@163.com" <sh_def@163.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: RE: [PATCH v2] mm/compaction:let proactive compaction order configurable
Date: Thu, 22 Apr 2021 16:27:00 +0000
Message-ID: <BYAPR12MB3416361959DA9128870E92B7D8469@BYAPR12MB3416.namprd12.prod.outlook.com> (raw)
In-Reply-To: <1618989713-20962-1-git-send-email-chukaiping@baidu.com>



> -----Original Message-----
> From: chukaiping <chukaiping@baidu.com>
> Sent: Wednesday, April 21, 2021 12:22 AM
> To: mcgrof@kernel.org; keescook@chromium.org; yzaikin@google.com;
> akpm@linux-foundation.org; vbabka@suse.cz; Nitin Gupta
> <nigupta@nvidia.com>; bhe@redhat.com; khalid.aziz@oracle.com;
> iamjoonsoo.kim@lge.com; mateusznosek0@gmail.com; sh_def@163.com
> Cc: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org; linux-
> mm@kvack.org
> Subject: [PATCH v2] mm/compaction:let proactive compaction order
> configurable
> 
> Currently the proactive compaction order is fixed to
> COMPACTION_HPAGE_ORDER(9), it's OK in most machines with lots of
> normal 4KB memory, but it's too high for the machines with small normal
> memory, for example the machines with most memory configured as 1GB
> hugetlbfs huge pages. In these machines the max order of free pages is often
> below 9, and it's always below 9 even with hard compaction. This will lead to
> proactive compaction be triggered very frequently. In these machines we only
> care about order of 3 or 4.
> This patch export the oder to proc and let it configurable by user, and the
> default value is still COMPACTION_HPAGE_ORDER.
>

I agree with the idea of making the target order configurable as you may not
always care about the hugepage order in particular.
 
> Signed-off-by: chukaiping <chukaiping@baidu.com>
> Reported-by: kernel test robot <lkp@intel.com>
> ---
> 
> Changes in v2:
>     - fix the compile error in ia64 and powerpc
>     - change the hard coded max order number from 10 to MAX_ORDER - 1
> 
>  include/linux/compaction.h |    1 +
>  kernel/sysctl.c            |   11 +++++++++++
>  mm/compaction.c            |   14 +++++++++++---
>  3 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h index
> ed4070e..151ccd1 100644
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -83,6 +83,7 @@ static inline unsigned long compact_gap(unsigned int
> order)  #ifdef CONFIG_COMPACTION  extern int sysctl_compact_memory;
> extern unsigned int sysctl_compaction_proactiveness;
> +extern unsigned int sysctl_compaction_order;
>  extern int sysctl_compaction_handler(struct ctl_table *table, int write,
>                         void *buffer, size_t *length, loff_t *ppos);  extern int
> sysctl_extfrag_threshold; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index
> 62fbd09..a607d4d 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -195,6 +195,8 @@ enum sysctl_writes_mode {  #endif /* CONFIG_SMP
> */  #endif /* CONFIG_SCHED_DEBUG */
> 
> +static int max_buddy_zone = MAX_ORDER - 1;
> +
>  #ifdef CONFIG_COMPACTION
>  static int min_extfrag_threshold;
>  static int max_extfrag_threshold = 1000; @@ -2871,6 +2873,15 @@ int
> proc_do_static_key(struct ctl_table *table, int write,
>                 .extra2         = &one_hundred,
>         },
>         {
> +               .procname       = "compaction_order",
> +               .data           = &sysctl_compaction_order,
> +               .maxlen         = sizeof(sysctl_compaction_order),
> +               .mode           = 0644,
> +               .proc_handler   = proc_dointvec_minmax,
> +               .extra1         = SYSCTL_ZERO,

This should be SYSCTL_ONE. Fragmentation wrt order 0 is always going to be 0.

Thanks,
Nitin


  reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-21  7:21 chukaiping
2021-04-22 16:27 ` Nitin Gupta [this message]
2021-04-22 20:33 ` Rafael Aquini
  -- strict thread matches above, loose matches on Subject: below --
2021-04-16 17:22 chukaiping
2021-04-16 21:31 ` David Rientjes
2021-04-19 12:02   ` 答复: " Chu,Kaiping

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