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Date: Mon, 03 May 2010 11:29:39 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: Jiri Slaby <jslaby@...e.cz> Cc: Avi Kivity <avi@...hat.com>, Changli Gao <xiaosuo@...il.com>, Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>, akpm@...ux-foundation.org, paulmck@...ux.vnet.ibm.com, adobriyan@...il.com, mingo@...e.hu, peterz@...radead.org, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] fs: use kmalloc() to allocate fdmem if possible Le lundi 03 mai 2010 à 11:19 +0200, Jiri Slaby a écrit : > On 05/03/2010 11:13 AM, Eric Dumazet wrote: > > /* > > * Warning: if size is not a power of two, kmalloc() might > > * waste memory because of its requirements. > > */ > > void *kvmalloc(size_t size) > > { > > void *ptr = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); > > This is kind of waste of high-order pages, isn't it? Wouldn't it be > better to have a watermark where we skip kmalloc completely? > > There are many drawbacks using kmalloc() instead of vmalloc(). (NUMA comes to mind, if you want a zone spreaded on all available nodes) So this kvmalloc() is not meant to be a generic replacement of all vmalloc() users, only selected ones. In some spots, allocating 8192 bytes in a driver setup for example, it should be fine. Using a high order page for this is perfect, as long as we can have a fallback to vmalloc() grep bnx2_alloc_mem /proc/vmallocinfo 0xf8690000-0xf8692000 8192 bnx2_alloc_mem+0x111/0x6d0 pages=1 vmalloc -- 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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