From: Matthew Wilcox <willy@infradead.org>
To: Yang Yang <yang.yang29@zte.com.cn>
Cc: akpm@linux-foundation.org, mhocko@suse.com,
pavel.tatashin@microsoft.com, vbabka@suse.cz, osalvador@suse.de,
rppt@linux.vnet.ibm.com, iamjoonsoo.kim@lge.com,
alexander.h.duyck@linux.intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, zhong.weidong@zte.com.cn,
wang.yi59@zte.com.cn
Subject: Re: [PATCH] mm: do not consider SWAP to calculate available when not necessary
Date: Sun, 25 Nov 2018 18:01:15 -0800 [thread overview]
Message-ID: <20181126020115.GF3065@bombadil.infradead.org> (raw)
In-Reply-To: <1543190303-8121-1-git-send-email-yang.yang29@zte.com.cn>
On Mon, Nov 26, 2018 at 07:58:23AM +0800, Yang Yang wrote:
> When si_mem_available() calculates 'available', it takes SWAP
> into account. But if CONFIG_SWAP is N or SWAP is off(some embedded system
> would like to do that), there is no need to consider it.
I don't understand this patch. The pagecache can be written back to
storage if it is dirty, regardless of whether there is swap space.
> @@ -4724,9 +4726,13 @@ long si_mem_available(void)
> * Not all the page cache can be freed, otherwise the system will
> * start swapping. Assume at least half of the page cache, or the
> * low watermark worth of cache, needs to stay.
> + * But if CONFIG_SWAP is N or SWAP is off, do not consider it.
> */
> pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
> - pagecache -= min(pagecache / 2, wmark_low);
> +#ifdef CONFIG_SWAP
> + if (i.totalswap > 0)
> + pagecache -= min(pagecache / 2, wmark_low);
> +#endif
> available += pagecache;
>
> /*
> --
> 2.15.2
>
next prev parent reply other threads:[~2018-11-26 2:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-25 23:58 [PATCH] mm: do not consider SWAP to calculate available when not necessary Yang Yang
2018-11-26 2:01 ` Matthew Wilcox [this message]
2018-11-26 7:41 ` Vlastimil Babka
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