From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Rostedt <rostedt@goodmis.org>
Subject: Re: change kmalloc into vmalloc for large memory
	allocations
Date: Fri, 28 Feb 2014 09:11:38 -0500
Message-ID: <20140228091138.39b90f52@gandalf.local.home>
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To: "Wang, Yalin" <Yalin.Wang@sonymobile.com>
Cc: "'alsa-devel@alsa-project.org'" <alsa-devel@alsa-project.org>, "'linux-usb@vger.kernel.org'" <linux-usb@vger.kernel.org>, "'tiwai@suse.de'" <tiwai@suse.de>, "'fweisbec@gmail.com'" <fweisbec@gmail.com>, "'dmitry.torokhov@gmail.com'" <dmitry.torokhov@gmail.com>, "'mingo@redhat.com'" <mingo@redhat.com>, "'linux-input@vger.kernel.org'" <linux-input@vger.kernel.org>, "'rydberg@euromail.se'" <rydberg@euromail.se>, "'lrg@ti.com'" <lrg@ti.com>, "'pablo@netfilter.org'" <pablo@netfilter.org>, "'coreteam@netfilter.org'" <coreteam@netfilter.org>, "'linux-arm-msm@vger.kernel.org'" <linux-arm-msm@vger.kernel.org>, "'netfilter@vger.kernel.org'" <netfilter@vger.kernel.org>, "'linux-arm-kernel@lists.infradead.org'" <linux-arm-kernel@lists.infradead.org>, "'gregkh@linuxfoundation.org'" <gregkh@linuxfoundation.org>, "'broonie@opensource.wolfsonmicro.com'" <broonie@opensource.wolfsonmicro.>
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On Fri, 28 Feb 2014 16:15:23 +0800
"Wang, Yalin" <Yalin.Wang@sonymobile.com> wrote:

> Kfree(ptr)
> {
> 	If (is_vmalloc_addr(ptr))
> 		Vfree(ptr);
> 	Else
> 		Kfree(ptr);
> }
> 
> 
> But we need add some flags to ensure always use kmalloc for
> Some special use (dma etc..)
> 
> How do you think of it ?

But vmalloc also takes up tlb entries. The more vmalloc space you have,
the more tlb entries that will need to be used, which will have a
performance affect on the entire system.

I would be against making kmalloc() secretly doing a vmalloc. If it is
better for a driver to use a vmalloc on large items, than change the
driver. Don't change a core function.

-- Steve