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Date: Wed, 5 Jun 2013 08:55:08 -0500 From: Seth Jennings <sjenning@...ux.vnet.ibm.com> To: Bob Liu <bob.liu@...cle.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Nitin Gupta <ngupta@...are.org>, Minchan Kim <minchan@...nel.org>, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, Dan Magenheimer <dan.magenheimer@...cle.com>, Robert Jennings <rcj@...ux.vnet.ibm.com>, Jenifer Hopper <jhopper@...ibm.com>, Mel Gorman <mgorman@...e.de>, Johannes Weiner <jweiner@...hat.com>, Rik van Riel <riel@...hat.com>, Larry Woodman <lwoodman@...hat.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Dave Hansen <dave@...1.net>, Joe Perches <joe@...ches.com>, Joonsoo Kim <iamjoonsoo.kim@....com>, Cody P Schafer <cody@...ux.vnet.ibm.com>, Hugh Dickens <hughd@...gle.com>, Paul Mackerras <paulus@...ba.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org Subject: Re: [PATCHv13 2/4] zbud: add to mm/ On Wed, Jun 05, 2013 at 02:43:28PM +0800, Bob Liu wrote: > Hi Seth, > > On 06/04/2013 04:33 AM, Seth Jennings wrote: > > + /* Couldn't find unbuddied zbud page, create new one */ > > How about moving zswap_is_full() to here. > > if (zswap_is_full()) { > /* Don't alloc any new page, try to reclaim and direct use the > reclaimed page instead */ Yes, this is at the top of the list for improvements. I have already started on this work and it isn't quite as simple as it seems. The difficulty rises from the fact that, for now, zswap uses per-cpu compression buffers which require preemption to be disabled. This prevents the calling zbud_reclaim_page() in zbud_alloc() because the eviction handler for the user may do something that can wait; an allocation with GFP_WAIT for example. So it's going to take some massaging in the zswap layer to get that to work. It's very doable. Just not in this patchset without causing a lot of code thrash. > } > > > + spin_unlock(&pool->lock); > > + page = alloc_page(gfp); > > + if (!page) > > + return -ENOMEM; > > + spin_lock(&pool->lock); > > + pool->pages_nr++; > > + zhdr = init_zbud_page(page); > > + bud = FIRST; <snip> > > It looks good for me except two things. > One is about what the performance might be after the zswap pool is full. > The other is still about the 20% limit of zswap pool size. Yep, working on both of them. Seth -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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