From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 25 Jan 2008 06:50:19 GMT
Subject: Re: I'm a total push-over..
Message-ID: <7vejc6761g.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <alpine.LFD.1.00.0801221913500.1741@woody.linux-foundation.org>

Linus Torvalds <torvalds@linux-foundation.org> writes:

> +static inline size_t estimate_cache_size(size_t ondisk_size, unsigned int entries)
> +{
> +	long per_entry;
> +
> +	per_entry = sizeof(struct cache_entry) - sizeof(struct ondisk_cache_entry);
> +
> +	/*
> +	 * Alignment can cause differences. This should be "alignof", but 
> +	 * since that's a gcc'ism, just use the size of a pointer.
> +	 */
> +	per_entry += sizeof(void *);
> +	return ondisk_size + entries*per_entry;
> +}
> +

I wonder if the issue Dave Miller addressed with
69ae517541ed5ab7d4fdcd8f82a9b8bd949df347 (fast-import: fix
unalinged allocation and access) applies here.

commit 69ae517541ed5ab7d4fdcd8f82a9b8bd949df347
Author: David S. Miller <davem@davemloft.net>
Date:   Fri Dec 14 20:39:16 2007 -0800

    fast-import: fix unalinged allocation and access
    
    The specialized pool allocator fast-import uses aligned objects on the
    size of a pointer, which was not sufficient at least on Sparc.  Instead,
    make the alignment for objects of type unitmax_t.
    
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Junio C Hamano <gitster@pobox.com>