Linear Address Spaces: Unsafe at any speed [article]

By: Adrian (a.delete@this.acm.org), July 1, 2022 9:58 pm
Room: Moderated Discussions
Foo_ (foo.delete@this.nomail.com) on July 1, 2022 3:21 am wrote:
> Adrian (a.delete@this.acm.org) on June 30, 2022 9:43 am wrote:
> >
> > When all the allocation and free requests are done from stacks, each stack corresponding
> > to a certain size class, nothing ever changes from the point of view of fragmentation.
>
> This is delusional. Allocation may be done "from stacks", but given that deallocations
> happen in random order (random from the POV of the allocator, of course), they
> cannot be done in a simple stack-like (i.e. LIFO) fashion.


When the size is variable, you are right.

But when the size of a memory block is fixed (being used to satisfy any allocation requests between 2 thresholds), the allocations and deallocations are really done as LIFO from the stack containing the free memory blocks.

A "malloc" pops a free memory block from the stack and a "free" pushes the used memory block back in the stack, regardless how many other "malloc" and "free" have happened meanwhile.

You are probably confused by thinking about a stack implemented as an array with a stack pointer. For this application, the stacks are implemented as linked lists, not as arrays.
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TopicPosted ByDate
Linear Address Spaces: Unsafe at any speed [article]Kester L2022/06/29 01:49 PM
  Linear Address Spaces: Unsafe at any speed [article]Rayla2022/06/29 02:14 PM
    Linear Address Spaces: Unsafe at any speed [article]Kester L2022/06/29 02:43 PM
      Not just worse-is-betterMark Roulo2022/06/29 03:21 PM
        Not just worse-is-better---2022/06/29 07:07 PM
  Linear Address Spaces: Unsafe at any speed [article]2022/06/30 12:08 AM
    Linear Address Spaces: Unsafe at any speed [article]Groo2022/06/30 12:56 PM
      Linear Address Spaces: Unsafe at any speed [article]Michael S2022/06/30 02:17 PM
  Linear Address Spaces: Unsafe at any speed [article]Eric Fink2022/06/30 01:43 AM
  Linear Address Spaces: Unsafe at any speed [article]dmcq2022/06/30 03:17 AM
  Linear Address Spaces: Unsafe at any speed [article]Adrian2022/06/30 05:36 AM
    Linear Address Spaces: Unsafe at any speed [article]anonymou52022/06/30 07:28 AM
      Linear Address Spaces: Unsafe at any speed [article]Anon42022/06/30 04:37 PM
        Linear Address Spaces: Unsafe at any speed [article]anonymou52022/06/30 06:19 PM
          Linear Address Spaces: Unsafe at any speed [article]dmcq2022/07/01 04:16 AM
            Linear Address Spaces: Unsafe at any speed [article]anonymou52022/07/01 05:40 AM
              Linear Address Spaces: Unsafe at any speed [article]dmcq2022/07/01 06:11 AM
                Linear Address Spaces: Unsafe at any speed [article]anonymou52022/07/01 08:09 AM
              Linear Address Spaces: Unsafe at any speed [article]dmcq2022/07/01 06:11 AM
                Why the duplicates?dmcq2022/07/01 06:18 AM
              Linear Address Spaces: Unsafe at any speed [article]2022/07/01 10:41 PM
    Linear Address Spaces: Unsafe at any speed [article]Foo_2022/06/30 07:43 AM
      Fragmentation: Both Size and LifetimeMark Roulo2022/06/30 08:25 AM
        Fragmentation: Both Size and Lifetime2022/06/30 10:09 AM
          Fragmentation: Both Size and Lifetimedmcq2022/06/30 11:12 AM
          Fragmentation: Both Size and LifetimeBrendan2022/06/30 04:08 PM
            Fragmentation: Both Size and Lifetime2022/07/02 03:12 AM
              Fragmentation: Both Size and LifetimeBrendan2022/07/02 01:56 PM
                Fragmentation: Both Size and Lifetime2022/07/04 05:34 AM
                  Fragmentation: Both Size and LifetimeBrendan2022/07/04 06:33 AM
                    Fragmentation: Both Size and Lifetime2022/07/04 07:35 AM
                      Fragmentation: Both Size and LifetimeBrendan2022/07/04 04:21 PM
                    Atom is just living at the Dunning-Krueger peakHeikki Kultala2022/07/04 09:26 AM
                      Atom is just living at the Dunning-Krueger peak2022/07/04 09:57 AM
      Linear Address Spaces: Unsafe at any speed [article]Adrian2022/06/30 08:31 AM
        Linear Address Spaces: Unsafe at any speed [article]Foo_2022/06/30 09:07 AM
          Linear Address Spaces: Unsafe at any speed [article]Adrian2022/06/30 09:43 AM
            Linear Address Spaces: Unsafe at any speed [article]Foo_2022/07/01 03:21 AM
              Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/01 09:58 PM
                Linear Address Spaces: Unsafe at any speed [article]Foo_2022/07/03 02:45 AM
                  Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/03 10:04 PM
                    Linear Address Spaces: Unsafe at any speed [article]ananon2022/07/04 02:35 AM
                    Linear Address Spaces: Unsafe at any speed [article]Foo_2022/07/04 03:11 AM
                      Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/05 01:36 AM
                    Linear Address Spaces: Unsafe at any speed [article]2022/07/04 04:18 AM
                    Linear Address Spaces: Unsafe at any speed [article]TAG2022/07/04 07:50 AM
                    Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/04 04:54 PM
                      Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/04 05:05 PM
                      Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/05 02:18 AM
                        Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/06 05:16 PM
                          Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/07 12:33 AM
        Linear Address Spaces: Unsafe at any speed [article]2022/06/30 10:40 AM
    Linear Address Spaces: Unsafe at any speed [article]---2022/06/30 08:28 AM
      Linear Address Spaces: Unsafe at any speed [article]Michael S2022/06/30 01:00 PM
    Linear Address Spaces: Unsafe at any speed [article]Jörn Engel2022/06/30 05:34 PM
      Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/01 12:55 AM
        Sorry, typo correctionAdrian2022/07/01 01:04 AM
        Linear Address Spaces: Unsafe at any speed [article]2022/07/01 04:01 AM
          Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/01 11:00 PM
            Linear Address Spaces: Unsafe at any speed [article]rwessel2022/07/02 07:16 AM
        Linear Address Spaces: Unsafe at any speed [article]Jörn Engel2022/07/01 09:40 AM
          Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/01 11:15 PM
  Linear Address Spaces: Unsafe at any speed [article]Brendan2022/06/30 11:09 AM
    Linear Address Spaces: Unsafe at any speed [article]dmcq2022/06/30 11:20 AM
      Linear Address Spaces: Unsafe at any speed [article]Brendan2022/06/30 03:52 PM
        Linear Address Spaces: Unsafe at any speed [article]dmcq2022/07/01 06:06 AM
          Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/01 01:24 PM
            Linear Address Spaces: Unsafe at any speed [article]rwessel2022/07/01 08:55 PM
  Linear Address Spaces - Free lunch?Björn Ragnar Björnsson2022/07/02 06:44 PM
    Linear Address Spaces - Free lunch?dmcq2022/07/03 04:30 AM
      Linear Address Spaces - Free lunch?Björn Ragnar Björnsson2022/07/03 04:50 PM
  Linear Address Spaces: Unsafe at any speed [article]Paul A. Clayton2022/07/18 07:49 AM
    Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/18 10:21 AM
      Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/18 03:11 PM
        Linear Address Spaces: Unsafe at any speed [article]anon22022/07/18 04:54 PM
          Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/18 10:22 PM
            Linear Address Spaces: Unsafe at any speed [article]Michael S2022/07/19 01:00 AM
              Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/19 05:50 AM
        Linear Address Spaces: Unsafe at any speed [article]Adrian2022/07/18 11:02 PM
          Linear Address Spaces: Unsafe at any speed [article]Brendan2022/07/19 08:29 PM
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