From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] kexec: Add --lite option
Date: Mon, 07 Dec 2015 13:16:06 +0000 [thread overview]
Message-ID: <56658696.6070103@arm.com> (raw)
In-Reply-To: <20151207114839.GF16406@dhcppc13.redhat.com>
Hi Pratyush,
On 07/12/15 11:48, Pratyush Anand wrote:
>> 1) When we execute kexec() system call in first kernel, at that time it
>> calculates sha256 on all the binaries [1]. It take almost un-noticeable time
>> (less than a sec) there.
>>
>> 2) When purgatory is executed then it re-calculates sha256 using same routines
>> [2] on same binary data as that of case (1). But, now it takes 10-20 sec
>> (depending of size of binaries)?
>>
>> Why did not it take same time with O2 + D-cache enabled? I think, we should be
>> able to achieve same time in second case as well. What is missing?
I haven't benchmarked this, but:
util_lib/sha256.c contains calls out to memcpy().
In your case 1, this will use the glibc version. In case 2, it will use
the version implemented in purgatory/string.c, which is a byte-by-byte copy.
Thanks,
James
next prev parent reply other threads:[~2015-12-07 13:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1445469125.30908.105.camel@infradead.org>
[not found] ` <20151022031718.GB11227@dhcp-129-115.nay.redhat.com>
[not found] ` <20151022125012.GB20847@redhat.com>
[not found] ` <1445540891.30908.144.camel@infradead.org>
[not found] ` <1446703011.12676.83.camel@freescale.com>
[not found] ` <20151207114547.GE16406@dhcppc13.redhat.com>
2015-12-07 11:48 ` [PATCH] kexec: Add --lite option Pratyush Anand
2015-12-07 13:16 ` James Morse [this message]
2015-12-07 14:07 ` Pratyush Anand
2015-12-08 1:03 ` Scott Wood
2015-12-08 16:00 ` James Morse
2015-12-09 9:28 ` Pratyush Anand
2016-01-11 12:46 ` Pratyush Anand
2016-01-12 1:06 ` Simon Horman
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