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Date: Wed, 18 Oct 2017 05:34:28 -0700
From: Matthew Wilcox <willy@infradead.org>
To: Srividya Desireddy <srividya.dr@samsung.com>
Cc: "sjenning@redhat.com" <sjenning@redhat.com>,
        "ddstreet@ieee.org" <ddstreet@ieee.org>,
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        "penberg@kernel.org" <penberg@kernel.org>,
        Dinakar Reddy Pathireddy <dinakar.p@samsung.com>,
        SHARAN ALLUR <sharan.allur@samsung.com>,
        RAJIB BASU <rajib.basu@samsung.com>, JUHUN KIM <juhunkim@samsung.com>,
        "srividya.desireddy@gmail.com" <srividya.desireddy@gmail.com>
Subject: Re: [PATCH] zswap: Same-filled pages handling
Message-ID: <20171018123427.GA7271@bombadil.infradead.org>
References: <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1>
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On Wed, Oct 18, 2017 at 10:48:32AM +0000, Srividya Desireddy wrote:
> +static void zswap_fill_page(void *ptr, unsigned long value)
> +{
> +	unsigned int pos;
> +	unsigned long *page;
> +
> +	page = (unsigned long *)ptr;
> +	if (value == 0)
> +		memset(page, 0, PAGE_SIZE);
> +	else {
> +		for (pos = 0; pos < PAGE_SIZE / sizeof(*page); pos++)
> +			page[pos] = value;
> +	}
> +}

I think you meant:

static void zswap_fill_page(void *ptr, unsigned long value)
{
	memset_l(ptr, value, PAGE_SIZE / sizeof(unsigned long));
}

(and you should see significantly better numbers at least on x86;
I don't know if anyone's done an arm64 version of memset_l yet).