From: Fidaullah Noonari <fidaullah.noonari@emumba.com>
To: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>, dpdk-dev <dev@dpdk.org>
Subject: Re: [PATCH] eal: fixes the bug where rte_malloc() fails to allocates memory
Date: Tue, 5 Jul 2022 10:04:49 +0500 [thread overview]
Message-ID: <CACbCz_eQnMMuCnEv960_+0Ttr-EZZ1PRfvVt4Ug=B7CNpn6t5A@mail.gmail.com> (raw)
In-Reply-To: <CAEYuUWCnRZNwxiOHEeTHw0Gy9aFJRLZtvAG9g=smuUvUEMcFXg@mail.gmail.com>
Hi Dmitry,
> alloc_sz = RTE_ALIGN_CEIL(RTE_ALIGN_CEIL(elt_size, align) +
> MALLOC_ELEM_OVERHEAD, pg_sz);
>
I am submitting a patch regarding this
> 2. Alignment calculation depends on whether we allocated new pages or not:
>
> malloc_heap_alloc_on_heap_id(align = 0) ->
> heap_alloc(align = 1) ->
> find_suitable_element(align = RTE_CACHE_LINE_ROUNDUP(align))
>
> malloc_heap_alloc_on_heap_id(align = 0) ->
> alloc_more_mem_on_socket(align = 1) ->
> try_expand_heap() -> ... ->
> alloc_pages_on_heap(align = 1) ->
> find_suitable_element(align = 1)
I saw alloc_pages_on_heap() has a rollback if find_suitable_element()
fails to find element. Now if we remove find_suitable_element(), don't
we need to rollback, wouldn't it mean unnecessary allocation or is it
handled somewhere that I didn't understand.
On Sat, Jun 18, 2022 at 4:29 PM Dmitry Kozlyuk <dmitry.kozliuk@gmail.com> wrote:
>
> Hi Fidaullah,
>
> Thanks for the fix,
> Acked-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
>
>
> Anatoly, I noticed a couple of other things while testing this.
>
> 1. Consider:
>
> elt_size = pg_sz - MALLOC_ELEM_OVERHEAD
> rte_malloc(align=0) which is converted to align = 1.
>
> Obviously, such an element fits into one page, however:
>
> alloc_sz = RTE_ALIGN_CEIL(1 + pg_sz +
> (MALLOC_ELEM_OVERHEAD - MALLOC_ELEM_OVERHEAD),
> pg_sz) == 2 * pg_sz.
>
> This can unnecessarily hit an allocation limit from the system or EAL.
> I suggest, in both places:
>
> alloc_sz = RTE_ALIGN_CEIL(RTE_ALIGN_CEIL(elt_size, align) +
> MALLOC_ELEM_OVERHEAD, pg_sz);
>
> This would be symmetric with malloc_elem_can_hold().
>
> 2. Alignment calculation depends on whether we allocated new pages or not:
>
> malloc_heap_alloc_on_heap_id(align = 0) ->
> heap_alloc(align = 1) ->
> find_suitable_element(align = RTE_CACHE_LINE_ROUNDUP(align))
>
> malloc_heap_alloc_on_heap_id(align = 0) ->
> alloc_more_mem_on_socket(align = 1) ->
> try_expand_heap() -> ... ->
> alloc_pages_on_heap(align = 1) ->
> find_suitable_element(align = 1)
>
> Why do we call find_suitable_element() directly and not just return
> and repeat the heap_alloc() attempt?
next prev parent reply other threads:[~2022-07-05 5:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-25 5:18 Fidaullah Noonari
2022-06-16 7:53 ` David Marchand
2022-06-18 11:29 ` Dmitry Kozlyuk
2022-06-22 17:03 ` David Marchand
2022-06-22 21:18 ` Dmitry Kozlyuk
2022-07-05 5:04 ` Fidaullah Noonari [this message]
2022-06-23 7:50 ` David Marchand
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