From: Karel Zak <kzak@redhat.com>
To: Aurelien LAJOIE <orel@melix.net>
Cc: util-linux@vger.kernel.org
Subject: Re: [PATCH] libuuid: improve uuid_unparse() performance
Date: Wed, 25 Mar 2020 12:10:49 +0100 [thread overview]
Message-ID: <20200325111049.jypz2csy2hqxoegr@ws.net.home> (raw)
In-Reply-To: <20200324212625.6934-1-orel@melix.net>
On Tue, Mar 24, 2020 at 10:26:25PM +0100, Aurelien LAJOIE wrote:
> There is 2 improvements:
>
> * remove useless uuid_unpack,
> * directly print the hexa format from memory without using printf
> we can do this as the bytes order is the network byte order
I'm not sure, but are you sure that whole UUID is in big-endian order?
I think that last part (aka "node", 6 bytes) is not subject to swapping.
It seems uuid_unpack() does nothing with the last part of the UUID.
But your patch works on LE as well as on BE, so I probably miss
something :-)
> before took 382623 us
> after took 36740 us
>
> Big Endian OpenBSD:
> before took 3138172 us
> after took 180116 us
I guess all this is about sprintf(), another way would be to use
uuid_unpack() but avoid sprintf().
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
next prev parent reply other threads:[~2020-03-25 11:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 21:26 [PATCH] libuuid: improve uuid_unparse() performance Aurelien LAJOIE
2020-03-25 11:10 ` Karel Zak [this message]
2020-03-26 0:54 ` Aurélien Lajoie
2020-03-25 14:16 ` Peter Cordes
2020-03-26 1:06 ` Aurélien Lajoie
2020-03-26 2:13 ` Peter Cordes
2020-03-26 23:22 ` Peter Cordes
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