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Re: ubc and removable devices
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Re: ubc and removable devices




On Nov 10, 2009, at 7:53 AM, Stefan Haller wrote:

Did you try the "purge" command-line tool?

Yes but it doesn't evict mmap-ed dynamic libraries. You need to allocate 2x physical memory for it to happen.

I have 4Gb of physical memory so allocating twice that
and then touching every page (below) takes over 4 minutes.
It's much faster to place the app on a removable device and
then eject the device to purge the caches of the app data.

I haven't looked for this behavior in the kernel source code
but it seems to be consistent and logical when I think about it.

Another alternative is rebooting but that takes about a minute
and requires me to restore all the apps I have running.

---

#!/usr/bin/env python

import mmap

SIZE = 8589934592L # 8Gb

map = mmap.mmap(-1, SIZE)
map[::4096] = '\x01' * (SIZE // 4096)

---

#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>

static long SIZE = 8589934592L;

int main(int argc, char**argv)
{
char *result = mmap(0, SIZE, PROT_READ|PROT_WRITE, MAP_ANON| MAP_PRIVATE, -1, 0);
if (result != MAP_FAILED)
{
unsigned long i;


    for (i = 0; i < SIZE; i += 4096)
      result[i] = 1;
    return 0;
  }
  return 1;
}

---
firefox for android!
http://wagerlabs.com

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 >Re: ubc and removable devices (From: email@hidden (Stefan Haller))



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