From: Hugh Dickins <email@example.com>
To: PINTU KUMAR <firstname.lastname@example.org>
Cc: "email@example.com" <firstname.lastname@example.org>,
Subject: Re: [Help] : RSS/PSS showing 0 during smaps for Xorg
Date: Mon, 30 Jan 2012 10:49:39 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.email@example.com> (raw)
[-- Attachment #1: Type: TEXT/PLAIN, Size: 2331 bytes --]
On Mon, 30 Jan 2012, PINTU KUMAR wrote:
> >If these are ordinary pages with struct pages, then you could probably
> >use a loop of vm_insert_page()s to insert them at mmap time, or a fault
> >routine to insert them on fault. But as I said, I don't know if this
> >memory is part of the ordinary page pool or not.
> You suggestion about using vm_insert_page() instead of remap_pfn_range worked for me and I got the Rss/Pss information for my driver.
Oh, I'm glad that happened to work for you.
> But still there is one problem related to page fault.
> If I remove remap_pfn_range then I get a page fault in the beginning.
> I tried to use the same vm_insert_page() during page_fault_handler for each vmf->virtual_address but it did not work.
> So for time being I remove the page fault handler from my vm_operations.
> But with these my menu screen(LCD screen) is not behaving properly (I get colorful lines on my LCD).
> So I need to handle the page fault properly.
> But I am not sure what is that I need to do inside page fault handler. Do you have any example or references or suggestions?
Sounds like you're not using vm_insert_page() properly: I would not expect
you to get a page fault there once you've set up the area with a loop of
Check the comments above it in mm/memory.c ("Your vma protection will
have to be set up correctly" might be relevant).
Compare how you're using it with other users of vm_insert_page() in
the kernel tree. Sorry, I don't have time to do your debugging.
> >Really, the question has to be, why do you need to see non-0s there?
> I want Rss/Pss value to account for how much video memory is used by the driver for the menu-screen,Xorg processes.
So, userspace does an mmap for a large-enough window, but only some part of
that is filled by the driver (whether by remap_pfn_range or vm_insert_pages),
and you'd like to communicate back how much via the Rss, instead of adding
some ioctl or sysfs interface to the driver? Fair enough.
I expect userspace could also work it out by touching pages of the area
until it gets a SIGBUS, but that might be too dirty a way of finding out.
Hmm, SIGBUS: maybe that's related to the faults that are puzzling you:
perhaps you're mapping less than you need to.
next prev parent reply other threads:[~2012-01-30 18:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1327310360.96918.YahooMailNeo@web162003.mail.bf1.yahoo.com>
2012-01-23 10:15 ` [Help] : RSS/PSS showing 0 during smaps for Xorg PINTU KUMAR
2012-01-23 19:31 ` Hugh Dickins
2012-01-25 5:22 ` PINTU KUMAR
2012-01-26 0:59 ` Hugh Dickins
2012-01-30 8:42 ` PINTU KUMAR
2012-01-30 18:49 ` Hugh Dickins [this message]
2012-02-01 14:49 ` PINTU KUMAR
2012-02-02 5:20 ` Hugh Dickins
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