linux-kernel - Re: [PATCH] xen-blkback: allocate list of pending reqs in small chunks

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Message-ID: <517A938C.6060703@citrix.com>
Date:	Fri, 26 Apr 2013 15:47:40 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	Roger Pau Monne <roger.pau@...rix.com>
CC:	"xen-devel@...ts.xen.org" <xen-devel@...ts.xen.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [PATCH] xen-blkback: allocate list of pending reqs in small chunks

On 26/04/13 14:45, Roger Pau Monne wrote:
> Allocate pending requests in smaller chunks instead of allocating them
> all at the same time.
> 
> This change also removes the global array of pending_reqs, it is no
> longer necessay.
> 
> Variables related to the grant mapping have been grouped into a struct
> called "grant_page", this allows to allocate them in smaller chunks,
> and also improves memory locality.
> 
[...]
> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
> index afab208..2841c0f 100644
> --- a/drivers/block/xen-blkback/xenbus.c
> +++ b/drivers/block/xen-blkback/xenbus.c
> @@ -127,22 +128,53 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
>         blkif->free_pages_num = 0;
>         atomic_set(&blkif->persistent_gnt_in_use, 0);
> 
> -       blkif->pending_reqs = kcalloc(XEN_BLKIF_REQS,
> -                                     sizeof(blkif->pending_reqs[0]),
> -                                     GFP_KERNEL);
> -       if (!blkif->pending_reqs) {
> -               kmem_cache_free(xen_blkif_cachep, blkif);
> -               return ERR_PTR(-ENOMEM);
> -       }
>         INIT_LIST_HEAD(&blkif->pending_free);
> +
> +       pr_alert("sizeof req: %lu\n", sizeof(*req));

Stray pr_alert() here.

Looks good otherwise.

Reviewed-by: David Vrabel <david.vrabel@...rix.com>

David
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