From:   David Laight <David.Laight@ACULAB.COM>
To:     =?iso-8859-1?Q?=27Thomas_Wei=DFschuh=27?= <linux@weissschuh.net>,
        "Josh Poimboeuf" <jpoimboe@kernel.org>
CC:     Peter Zijlstra <peterz@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 0/8] objtool: reduce maximum memory usage
Thread-Topic: [PATCH v2 0/8] objtool: reduce maximum memory usage
Thread-Index: AQHZNSfK1Pp9dgy34k2krggntueDJq66C5XQ
Date:   Wed, 1 Feb 2023 12:51:46 +0000
Message-ID: <093273245f624bcab3fac9d391f6d249@AcuMS.aculab.com>
References: <20221216-objtool-memory-v2-0-17968f85a464@weissschuh.net>
 <20230129214339.76hyytrllggbvuat@t-8ch.de>
 <20230131000356.5u2siglndnjyarql@treble>
 <20230131035442.yzq4opasci7azt2j@t-8ch.de>
In-Reply-To: <20230131035442.yzq4opasci7azt2j@t-8ch.de>
Accept-Language: en-GB, en-US
MIME-Version: 1.0
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

From: Thomas Weißschuh.
> Sent: 31 January 2023 03:55
...
> I have another half-finished series that replaces the doubly-linked
> list_heads used by elf.h with a custom singly-linked list.
> This would save a few pointers per struct.
> 
> Do you think this is worth it?

If you allocate the structures in blocks of (say) 256 you
can use an array of pointers to the blocks and then a
32bit index instead of a 64bit pointer.

For real space-saving you might decide that the index can
never exceed 2^^24 and use a bitfield!

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)