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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-efi <linux-efi@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Arend Van Spriel <arend.vanspriel@broadcom.com>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@intel.com>,
	Eric Snowberg <eric.snowberg@oracle.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Joe Perches <joe@perches.com>, Jon Hunter <jonathanh@nvidia.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Prakhya, Sai Praneeth" <sai.praneeth.prakhya@intel.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	YiFei Zhu <zhuyifei1999@gmail.com>
Subject: Re: [PATCH 10/11] efi: reduce the amount of memblock reservations for persistent allocations
Date: Fri, 30 Nov 2018 09:39:34 +0100
Message-ID: <CAKv+Gu8aOK3rY0v0XsHp9wfHOo-F5cHE3VcLXu6k7WLB1R8UjQ@mail.gmail.com> (raw)
In-Reply-To: <20181130083823.GB97998@gmail.com>

On Fri, 30 Nov 2018 at 09:38, Ingo Molnar <mingo@kernel.org> wrote:
>
>
> * Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
>
> > The current implementation of efi_mem_reserve_persistent() is rather
> > naive, in the sense that for each invocation, it creates a separate
> > linked list entry to describe the reservation. Since the linked list
> > entries themselves need to persist across subsequent kexec reboots,
> > every reservation created this way results in two memblock_reserve()
> > calls at the next boot.
> >
> > On arm64 systems with 100s of CPUs, this may result in a excessive
> > number of memblock reservations, and needless fragmentation.
> >
> > So instead, make use of the newly updated struct linux_efi_memreserve
> > layout to put multiple reservations into a single linked list entry.
> > This should get rid of the numerous tiny memblock reservations, and
> > effectively cut the total number of reservations in half on arm64
> > systems with many CPUs.
> >
> > Tested-by: Marc Zyngier <marc.zyngier@arm.com>
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> >  drivers/firmware/efi/efi.c | 20 +++++++++++++++++---
> >  include/linux/efi.h        |  3 +++
> >  2 files changed, 20 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > index 80b11521627a..e90bc32c2670 100644
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -998,7 +998,8 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> >  {
> >       struct linux_efi_memreserve *rsv;
> >       int rsvsize = EFI_MEMRESERVE_SIZE(1);
> > -     int rc;
> > +     unsigned long prsv;
> > +     int rc, index;
> >
> >       if (efi_memreserve_root == (void *)ULONG_MAX)
> >               return -ENODEV;
> > @@ -1009,11 +1010,24 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> >                       return rc;
> >       }
> >
> > -     rsv = kmalloc(rsvsize, GFP_ATOMIC);
>
> I fixed the following build warning in this patch:
>
>   drivers/firmware/efi/efi.c:1000:6: warning: unused variable ‘rsvsize’ [-Wunused-variable]
>
> 'rsvsize' got entirely orphaned by the patch, so it can be removed.
>

Thanks, that was a rebase error on my part - apologies for not spotting it.

  reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-29 17:12 [GIT PULL 00/11] EFI updates Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service Ard Biesheuvel
2018-11-30  7:29   ` Ingo Molnar
2018-11-30  8:26     ` Ard Biesheuvel
2018-11-30  8:36       ` Ingo Molnar
2018-11-30  9:55   ` [tip:efi/core] " tip-bot for Eric Snowberg
2018-11-29 17:12 ` [PATCH 02/11] efi/fdt: Indentation fix Ard Biesheuvel
2018-11-30  7:56   ` [PATCH] efi/fdt: More cleanups Ingo Molnar
2018-11-30  8:31     ` Ard Biesheuvel
2018-11-30  9:48       ` Ingo Molnar
2018-11-30  9:56   ` [tip:efi/core] efi/fdt: Indentation fix tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 03/11] efi/fdt: Simplify get_fdt flow Ard Biesheuvel
2018-11-30  9:57   ` [tip:efi/core] efi/fdt: Simplify the get_fdt() flow tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 04/11] x86/mm/pageattr: Introduce helper function to unmap EFI boot services Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 05/11] x86/efi: Unmap EFI boot services code/data regions from efi_pgd Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-12-17 18:06     ` Prakhya, Sai Praneeth
2018-12-17 18:10       ` Ard Biesheuvel
2018-12-17 18:42         ` Prakhya, Sai Praneeth
2018-12-17 19:35           ` Ard Biesheuvel
2018-12-17 19:48             ` Prakhya, Sai Praneeth
2018-12-21 17:02               ` Ard Biesheuvel
2018-12-21 17:13                 ` Borislav Petkov
2018-12-21 17:26                   ` Ard Biesheuvel
2018-12-21 19:29                     ` Borislav Petkov
2018-12-22 11:07                       ` Ard Biesheuvel
2019-01-07 15:57                         ` Matt Fleming
2018-12-21 17:52                 ` Prakhya, Sai Praneeth
2018-11-29 17:12 ` [PATCH 06/11] x86/efi: Move efi_<reserve/free>_boot_services() to arch/x86 Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 07/11] efi/libstub: Disable some warnings for x86{,_64} Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Nathan Chancellor
2018-11-29 17:12 ` [PATCH 08/11] firmware: efi: add NULL pointer checks in efivars api functions Ard Biesheuvel
2018-11-30  8:11   ` Ingo Molnar
2018-11-30  8:37     ` Ard Biesheuvel
2018-11-30  9:56   ` [tip:efi/core] firmware/efi: Add NULL pointer checks in efivars API functions tip-bot for Arend van Spriel
2018-11-29 17:12 ` [PATCH 09/11] efi: permit multiple entries in persistent memreserve data structure Ard Biesheuvel
2018-11-30 10:00   ` [tip:efi/core] efi: Permit " tip-bot for Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 10/11] efi: reduce the amount of memblock reservations for persistent allocations Ard Biesheuvel
2018-11-30  8:38   ` Ingo Molnar
2018-11-30  8:39     ` Ard Biesheuvel [this message]
2018-11-30 10:00   ` [tip:efi/core] efi: Reduce " tip-bot for Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 11/11] efi/x86: earlyprintk - Fix infinite loop on some screen widths Ard Biesheuvel
2018-11-30  8:05   ` Ingo Molnar
2018-11-30  8:32     ` Ard Biesheuvel
2018-11-30  9:55   ` [tip:efi/core] x86/earlyprintk/efi: " tip-bot for YiFei Zhu
2018-11-29 18:27 ` [GIT PULL 00/11] EFI updates Prakhya, Sai Praneeth
2018-11-30 12:01   ` Ard Biesheuvel
2018-11-30 18:01     ` Prakhya, Sai Praneeth

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