From: Okash Khawaja <okash.khawaja@gmail.com>
To: Carter Cheng <cartercheng@gmail.com>
Cc: kernelnewbies <kernelnewbies@kernelnewbies.org>
Subject: Re: where to find the kmalloc implementation
Date: Wed, 9 Jan 2019 16:51:40 +0000 [thread overview]
Message-ID: <CAOtcWM1gBXCXfihsQYxrfAz5B=DAYbRLLkXPZQE=40c4LYu0Zg@mail.gmail.com> (raw)
In-Reply-To: <CALS6=qVH1rHBOSycP2gqpNvoP2r4XX8fFw2L_0pV0km8wZ-1GQ@mail.gmail.com>
On Wed, Jan 9, 2019 at 3:17 PM Carter Cheng <cartercheng@gmail.com> wrote:
>
> Hi,
>
> I am curious where in the kernel sources would I find the kmalloc implementation? I am curious how GFP_ATOMIC option is implemented.
>
> Thanks,
>
> Carter.
Hi Carter,
kmalloc() implementation can be found in include/linux/slab.h.
Interesting part of kmalloc() is the use of kmem_cache. kmem_cache is
basically a pool of memory. kmalloc() maintains a system of
kmem_cache's and allocates memory from those caches to the caller. How
it allocates that memory is determined by type of request (e.g.
GFP_ATOMIC) and "buddy system" algorithm, which is an algorithm
designed to minimise fragmentation and be cache efficient.
From what I remember, kmalloc system sets aside memory for "emergency"
uses, like kmalloc calls with GFP_ATOMIC. So for normal memory
allocation calls, execution may sleep until memory becomes available,
even though there may be memory available in the emergence cache.
Hope it helps :)
Okash
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next prev parent reply other threads:[~2019-01-09 16:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 15:16 where to find the kmalloc implementation Carter Cheng
2019-01-09 16:51 ` Okash Khawaja [this message]
2019-01-10 13:51 ` Carter Cheng
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