From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Andrew Jones <andrew.jones@linux.dev>
Cc: pbonzini@redhat.com, thuth@redhat.com, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu, nikos.nikoleris@arm.com
Subject: Re: [kvm-unit-tests RFC PATCH 06/19] lib/alloc_phys: Remove allocation accounting
Date: Tue, 20 Sep 2022 14:19:28 +0100 [thread overview]
Message-ID: <Yym94MMavW1T33XM@e121798.cambridge.arm.com> (raw)
In-Reply-To: <20220920084047.gblxkhedbugl7giz@kamzik>
Hi,
On Tue, Sep 20, 2022 at 10:40:47AM +0200, Andrew Jones wrote:
> On Tue, Aug 09, 2022 at 10:15:45AM +0100, Alexandru Elisei wrote:
> > The page allocator has better allocation tracking and is used by all
> > architectures, while the physical allocator is now never used for
> > allocating memory.
> >
> > Simplify the physical allocator by removing allocation accounting. This
> > accomplishes two things:
> >
> > 1. It makes the allocator more useful, as the warning that was displayed
> > each allocation after the 256th is removed.
> >
> > 2. Together with the lock removal, the physical allocator becomes more
> > appealing as a very early allocator, when using the page allocator might
> > not be desirable or feasible.
>
> How does the locking cause problems when used in an early allocator?
By "early allocator" I mean here an allocator that can be used with the MMU
off.
The "desirable or feasible" part refers to the fact that the page allocator
cannot be used an early allocator (when the MMU is off) because 1. It
doesn't do the necessary cache maintenance operations and 2. It would be
hard to do add them, as the internal structures that the page allocator
maintains are significantly more complex than what the physical allocator
uses.
With this part: "together with the lock removal, the physical allocator
becomes more appealing as a very early allocator [..]" I was trying to say
that the physical allocator has now become as simple as it can possibly be
(well, align_min could also be removed and leave it up to the calling code
to request correctly aligned allocations but it's debatable if users of the
allocator should know about how it's implemented). I can reword or remove
this part if you feel it's confusing.
Thanks,
Alex
>
> >
> > Also, phys_alloc_show() has received a slight change in the way it displays
> > the use and free regions: the end of the region is now non-inclusive, to
> > allow phys_alloc_show() to express that no memory has been used, or no
> > memory is free, in which case the start and the end adresses are equal.
> >
> > Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> > ---
> > lib/alloc_phys.c | 65 ++++++++++++++----------------------------------
> > lib/alloc_phys.h | 5 ++--
> > 2 files changed, 21 insertions(+), 49 deletions(-)
> >
>
> Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
next prev parent reply other threads:[~2022-09-20 13:19 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 9:15 [kvm-unit-tests RFC PATCH 00/19] arm/arm64: Rework cache maintenance at boot Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 01/19] Makefile: Define __ASSEMBLY__ for assembly files Alexandru Elisei
2022-08-09 12:36 ` Nikos Nikoleris
2022-09-20 8:11 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 02/19] lib/alloc_phys: Initialize align_min Alexandru Elisei
2022-09-20 8:20 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 03/19] lib/alloc_phys: Use phys_alloc_aligned_safe and rename it to memalign_early Alexandru Elisei
2022-09-20 8:27 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 04/19] powerpc: Use the page allocator Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 05/19] lib/alloc_phys: Remove locking Alexandru Elisei
2022-09-20 8:45 ` Andrew Jones
2022-09-20 13:20 ` Alexandru Elisei
2022-09-20 14:59 ` Andrew Jones
2022-09-26 15:04 ` Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 06/19] lib/alloc_phys: Remove allocation accounting Alexandru Elisei
2022-09-20 8:40 ` Andrew Jones
2022-09-20 13:19 ` Alexandru Elisei [this message]
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 07/19] arm/arm64: Mark the phys_end parameter as unused in setup_mmu() Alexandru Elisei
2022-09-20 8:58 ` Andrew Jones
2022-09-26 11:01 ` Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 08/19] arm/arm64: Use pgd_alloc() to allocate mmu_idmap Alexandru Elisei
2022-09-20 9:05 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 09/19] arm/arm64: Zero secondary CPUs' stack Alexandru Elisei
2022-08-09 12:56 ` Nikos Nikoleris
2022-08-10 9:42 ` Alexandru Elisei
2022-08-10 10:00 ` Nikos Nikoleris
2022-09-20 9:24 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 10/19] arm/arm64: Enable the MMU early Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 11/19] arm/arm64: Map the UART when creating the translation tables Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 12/19] arm/arm64: assembler.h: Replace size with end address for dcache_by_line_op Alexandru Elisei
2022-08-09 13:01 ` Nikos Nikoleris
2022-09-20 9:37 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 13/19] arm: page.h: Add missing libcflat.h include Alexandru Elisei
2022-09-20 9:39 ` Andrew Jones
2022-09-26 11:02 ` Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 14/19] arm/arm64: Add C functions for doing cache maintenance Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 15/19] lib/alloc_phys: Add callback to perform " Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 16/19] arm/arm64: Allocate secondaries' stack using the page allocator Alexandru Elisei
2022-09-20 9:58 ` Andrew Jones
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 17/19] arm/arm64: Configure secondaries' stack before enabling the MMU Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 18/19] arm/arm64: Perform dcache maintenance at boot Alexandru Elisei
2022-08-09 9:15 ` [kvm-unit-tests RFC PATCH 19/19] arm/arm64: Rework the cache maintenance in asm_mmu_disable Alexandru Elisei
2022-08-09 13:53 ` Nikos Nikoleris
2022-08-09 14:22 ` Alexandru Elisei
2022-08-09 15:53 ` Nikos Nikoleris
2022-08-09 16:53 ` Alexandru Elisei
2022-08-09 19:48 ` Nikos Nikoleris
2022-08-10 8:52 ` Alexandru Elisei
2022-08-09 9:49 ` [kvm-unit-tests RFC PATCH 00/19] arm/arm64: Rework cache maintenance at boot Alexandru Elisei
2023-11-05 10:16 ` Alexandru Elisei
2023-11-06 9:37 ` Shaoqin Huang
2023-11-07 9:01 ` Alexandru Elisei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Yym94MMavW1T33XM@e121798.cambridge.arm.com \
--to=alexandru.elisei@arm.com \
--cc=andrew.jones@linux.dev \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=nikos.nikoleris@arm.com \
--cc=pbonzini@redhat.com \
--cc=thuth@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).