From: Ard Biesheuvel <ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk Cc: marc.zyngier@arm.com, bhsharma@redhat.com, linux-efi@vger.kernel.org, will.deacon@arm.com, Ard Biesheuvel <ard.biesheuvel@linaro.org> Subject: [PATCH v2 6/6] efi: reduce the amount of memblock reservations for persistent allocations Date: Wed, 7 Nov 2018 15:16:11 +0100 [thread overview] Message-ID: <20181107141611.12076-7-ard.biesheuvel@linaro.org> (raw) In-Reply-To: <20181107141611.12076-1-ard.biesheuvel@linaro.org> 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 | 29 ++++++++++++++------ include/linux/efi.h | 3 ++ 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 59f8ac93c759..347028cb392f 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -978,22 +978,35 @@ static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock); int efi_mem_reserve_persistent(phys_addr_t addr, u64 size) { struct linux_efi_memreserve *rsv, *parent; - int rsvsize = EFI_MEMRESERVE_SIZE(1); + unsigned long prsv; + int index; if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) return -ENODEV; - rsv = kmalloc(rsvsize, GFP_KERNEL); - if (!rsv) - return -ENOMEM; - parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB); - if (!parent) { - kfree(rsv); + if (!parent) return -ENOMEM; + + /* first try to find a slot in an existing linked list entry */ + for (prsv = parent->next; prsv; prsv = rsv->next) { + rsv = __va(prsv); + index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size); + if (index < rsv->size) { + rsv->entry[index].base = addr; + rsv->entry[index].size = size; + + memunmap(parent); + return 0; + } } - rsv->size = 1; + /* no slot found - allocate a new linked list entry */ + rsv = (struct linux_efi_memreserve *)__get_free_page(GFP_KERNEL); + if (!rsv) + return -ENOMEM; + + rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE); atomic_set(&rsv->count, 1); rsv->entry[0].base = addr; rsv->entry[0].size = size; diff --git a/include/linux/efi.h b/include/linux/efi.h index dfce82b2ca8a..1a1a081f7244 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1727,4 +1727,7 @@ struct linux_efi_memreserve { #define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \ (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0])) +#define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \ + / sizeof(((struct linux_efi_memreserve *)0)->entry[0])) + #endif /* _LINUX_EFI_H */ -- 2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 6/6] efi: reduce the amount of memblock reservations for persistent allocations Date: Wed, 7 Nov 2018 15:16:11 +0100 [thread overview] Message-ID: <20181107141611.12076-7-ard.biesheuvel@linaro.org> (raw) In-Reply-To: <20181107141611.12076-1-ard.biesheuvel@linaro.org> 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 | 29 ++++++++++++++------ include/linux/efi.h | 3 ++ 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 59f8ac93c759..347028cb392f 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -978,22 +978,35 @@ static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock); int efi_mem_reserve_persistent(phys_addr_t addr, u64 size) { struct linux_efi_memreserve *rsv, *parent; - int rsvsize = EFI_MEMRESERVE_SIZE(1); + unsigned long prsv; + int index; if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) return -ENODEV; - rsv = kmalloc(rsvsize, GFP_KERNEL); - if (!rsv) - return -ENOMEM; - parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB); - if (!parent) { - kfree(rsv); + if (!parent) return -ENOMEM; + + /* first try to find a slot in an existing linked list entry */ + for (prsv = parent->next; prsv; prsv = rsv->next) { + rsv = __va(prsv); + index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size); + if (index < rsv->size) { + rsv->entry[index].base = addr; + rsv->entry[index].size = size; + + memunmap(parent); + return 0; + } } - rsv->size = 1; + /* no slot found - allocate a new linked list entry */ + rsv = (struct linux_efi_memreserve *)__get_free_page(GFP_KERNEL); + if (!rsv) + return -ENOMEM; + + rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE); atomic_set(&rsv->count, 1); rsv->entry[0].base = addr; rsv->entry[0].size = size; diff --git a/include/linux/efi.h b/include/linux/efi.h index dfce82b2ca8a..1a1a081f7244 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1727,4 +1727,7 @@ struct linux_efi_memreserve { #define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \ (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0])) +#define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \ + / sizeof(((struct linux_efi_memreserve *)0)->entry[0])) + #endif /* _LINUX_EFI_H */ -- 2.19.1
next prev parent reply other threads:[~2018-11-07 14:16 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-07 14:16 [PATCH v2 0/6] arm/efi: fix memblock reallocation crash due to persistent reservations Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-07 14:16 ` [PATCH v2 1/6] arm64: memblock: don't permit memblock resizing until linear mapping is up Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-08 17:53 ` Catalin Marinas 2018-11-08 17:53 ` Catalin Marinas 2018-11-07 14:16 ` [PATCH v2 2/6] ARM: mm: permit memblock resizing right after mapping the linear region Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-07 14:16 ` [PATCH v2 3/6] ARM: mm: permit early_memremap() to be used in paging_init() Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-07 14:16 ` [PATCH v2 4/6] efi/arm: defer persistent reservations until after paging_init() Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-07 14:16 ` [PATCH v2 5/6] efi: permit multiple entries in persistent memreserve data structure Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel 2018-11-07 14:16 ` Ard Biesheuvel [this message] 2018-11-07 14:16 ` [PATCH v2 6/6] efi: reduce the amount of memblock reservations for persistent allocations Ard Biesheuvel 2018-11-08 19:13 ` [PATCH v2 0/6] arm/efi: fix memblock reallocation crash due to persistent reservations Bhupesh Sharma 2018-11-08 19:13 ` Bhupesh Sharma 2018-11-08 19:14 ` Bhupesh Sharma 2018-11-08 19:14 ` Bhupesh Sharma 2018-11-08 19:14 ` Ard Biesheuvel 2018-11-08 19:14 ` Ard Biesheuvel
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