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Date: Wed, 08 Jul 2009 11:06:24 -0700 (PDT) From: David Miller <davem@...emloft.net> To: michal.simek@...alogix.com Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, mingo@...e.hu, arnd@...db.de, lethal@...ux-sh.org, ltp-list@...ts.sourceforge.net Subject: Re: mmap hw behavior From: Michal Simek <michal.simek@...alogix.com> Date: Wed, 08 Jul 2009 20:03:27 +0200 > David Miller wrote: >> From: Michal Simek <michal.simek@...alogix.com> >> Date: Wed, 08 Jul 2009 19:03:11 +0200 >> >> >>> When I call mmap for that open file with pointer to calloc place >>> (first parameter, + length zero) it should be one tlb invalidation >>> for calloc and new tlb which connect open file. We check it and we >>> don't have any tlb invalidation that's why I think that kernel do >>> different thigs. Or is it there any copying? Or anything different? >>> >> >> There is no need to tlb flush the calloc area unless that memory area >> is actually touched by the user application and thus the page is >> faulted in. >> > That calloc area is filled by any value (in that test). Is it mean that > for this case when calloc area is touched > there must be tlb invalidation + remapping? Yes, if the calloc area is written to by the application, there should be a tlb flush when the mmap() overrides that virtual region with a different mapping. -- 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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