Re: [PATCH] speedup allocation in pack-redundant.c

From: Alex Riesen <raa.lkml@gmail.com>
Date: Nov 22, 2005, 23:00 UTC
Message-ID: <20051122230011.GA2916@steel.home>
In-Reply-To: <7vek58ct4b.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano, Tue, Nov 22, 2005 21:41:56 +0100:

Show 7 quoted lines

> > Reuse discarded nodes of llists
> >
> > Signed-off-by: Alex Riesen <ariesen@harmanbecker.com>
> 
> I think making allocation/deallocation to the central place is a
> good cleanup, but I am not sure about the free-nodes reusing.
> Does this make difference in real life?

It definitely does, though nor very much. I have no real numbers at hand (being home now), but I remember it was 1 min with against 3 min without the patch on cygwin+fat32, which is already bad enough all by itself. Very big repository with no redundant packs in it.

> If so, it might be worth doing the slab-like allocation, since
> free-nodes are very small structure and malloc overhead is not
> ignorable there.

Like this?

    if ( free_nodes ) { ... }
    else {
	struct llist_node *slab = malloc(sizeof(*slab) * BLKCNT);
	for ( i =0; i < BLKCNT; ++i ) {
	    slab->next = free_nodes;
	    free_nodes = slab++;
	}
    }