From: Paolo Bonzini <pbonzini@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 1/4] qjson: replace QString in JSONLexer with GString
Date: Wed, 25 Nov 2015 14:34:18 +0100 [thread overview]
Message-ID: <5655B8DA.4060808@redhat.com> (raw)
In-Reply-To: <87a8q2454l.fsf@blackfin.pond.sub.org>
On 25/11/2015 13:48, Markus Armbruster wrote:
> Where does the 3 come from?
My hat. :) I don't know---it was in the old patches, and I just brought
it on.
Oh, found it. GString adds 1 to the size (for the \0); allocating 4
bytes probably seemed like a good idea at the time.
However, it also computes the power of two that is >= size + 1, and
g_string_new uses 2 as the default length so it _also_ results in
allocating four bytes (ceil_pow2(2+1) == 4).
Paolo
> As long as g_string_truncate() doesn't reallocate, lexer->token will
> grow to hold the largest token seen so far, and stay there.
>
> Why not MAX_TOKEN_SIZE and be done with it? Oh, it's 64 MiB. Ookay,
> I'd call that... generous.
>
next prev parent reply other threads:[~2015-11-25 13:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-23 17:44 [Qemu-devel] [PATCH v2 for-2.5? 0/4] qjson: save a lot of memory Paolo Bonzini
2015-11-23 17:44 ` [Qemu-devel] [PATCH v2 1/4] qjson: replace QString in JSONLexer with GString Paolo Bonzini
2015-11-25 12:48 ` Markus Armbruster
2015-11-25 13:34 ` Paolo Bonzini [this message]
2015-11-23 17:44 ` [Qemu-devel] [PATCH v2 2/4] qjson: do not save/restore contexts Paolo Bonzini
2015-11-23 17:59 ` Laszlo Ersek
2015-11-23 18:09 ` Paolo Bonzini
2015-11-23 19:18 ` Laszlo Ersek
2015-11-23 20:05 ` Eric Blake
2015-11-23 20:26 ` Laszlo Ersek
2015-11-24 8:03 ` Gerd Hoffmann
2015-11-24 10:50 ` Laszlo Ersek
2015-11-24 11:18 ` Paolo Bonzini
2015-11-24 12:44 ` Fam Zheng
2015-11-24 12:54 ` Paolo Bonzini
2015-11-24 13:15 ` Markus Armbruster
2015-11-24 11:33 ` Gerd Hoffmann
2015-11-24 11:39 ` Laszlo Ersek
2015-11-25 14:32 ` Markus Armbruster
2015-11-23 17:44 ` [Qemu-devel] [PATCH v2 3/4] qjson: store tokens in a GQueue Paolo Bonzini
2015-11-23 17:44 ` [Qemu-devel] [PATCH v2 4/4] qjson: surprise, allocating 6 QObjects per token is expensive Paolo Bonzini
2015-11-23 21:00 ` [Qemu-devel] [PATCH v2 for-2.5? 0/4] qjson: save a lot of memory Eric Blake
2015-11-25 14:47 ` Markus Armbruster
2015-11-25 18:08 ` Paolo Bonzini
2015-11-25 18:34 ` Markus Armbruster
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