From mboxrd@z Thu Jan 1 00:00:00 1970 From: Przemyslaw Marczak Date: Wed, 18 Feb 2015 13:31:55 +0100 Subject: [U-Boot] [PATCH v2 2/8] arm: relocation: clear .bss section with arch memset if defined In-Reply-To: References: <1424099601-14979-1-git-send-email-p.marczak@samsung.com> <1424099601-14979-3-git-send-email-p.marczak@samsung.com> <54E20AEF.1080904@samsung.com> Message-ID: <54E4863B.3040509@samsung.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello, On 02/18/2015 05:32 AM, Simon Glass wrote: > Hi Przemyslaw, > > On 16 February 2015 at 08:21, Przemyslaw Marczak wrote: >> Hello, >> >> >> On 02/16/2015 04:13 PM, Przemyslaw Marczak wrote: >>> >>> For ARM architecture, enable the CONFIG_USE_ARCH_MEMSET/MEMCPY, >>> will highly increase the memset/memcpy performance. This is able >>> thanks to the ARM multiple register instructions. >>> >>> Unfortunatelly the relocation is done without the cache enabled, >>> so it takes some time, but zeroing the BSS memory takes much more >>> longer, especially for the configs with big static buffers. >>> >>> A quick test confirms, that the boot time improvement after using >>> the arch memcpy for relocation has no significant meaning. >>> The same test confirms that enable the memset for zeroing BSS, >>> reduces the boot time. >>> >>> So this patch enables the arch memset for zeroing the BSS after >>> the relocation process. For ARM boards, this can be enabled >>> in board configs by defining: 'CONFIG_USE_ARCH_MEMSET'. >>> >>> This was tested on Trats2. >>> A quick test with trace. Boot time from start to main_loop() entry: >>> - ~1384ms - before this change >>> - ~888ms - after this change >>> >>> Signed-off-by: Przemyslaw Marczak >>> Cc: Albert Aribaud >>> Cc: Tom Rini >>> --- >>> arch/arm/lib/crt0.S | 10 +++++++++- >>> 1 file changed, 9 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S >>> index 22df3e5..fab3d2c 100644 >>> --- a/arch/arm/lib/crt0.S >>> +++ b/arch/arm/lib/crt0.S >>> @@ -115,14 +115,22 @@ here: >>> bl c_runtime_cpu_setup /* we still call old routine here >>> */ >>> >>> ldr r0, =__bss_start /* this is auto-relocated! */ >>> - ldr r1, =__bss_end /* this is auto-relocated! */ >>> >>> +#ifdef CONFIG_USE_ARCH_MEMSET >>> + ldr r3, =__bss_end /* this is auto-relocated! */ >>> + mov r1, #0x00000000 /* prepare zero to clear BSS */ >>> + >>> + subs r2, r3, r0 /* r2 = memset len */ >>> + bl memset >>> +#else >>> + ldr r1, =__bss_end /* this is auto-relocated! */ >>> mov r2, #0x00000000 /* prepare zero to clear BSS */ >>> >>> clbss_l:cmp r0, r1 /* while not at end of BSS */ >>> strlo r2, [r0] /* clear 32-bit BSS word */ >>> addlo r0, r0, #4 /* move to next */ >>> blo clbss_l >>> +#endif >>> >>> bl coloured_LED_init >>> bl red_led_on >>> >> >> This commit left unchanged. After boot time test using oscilloscope and the >> clock cycle counter I didn't noticed a time difference in more then one ms. >> In this case I think that insert a duplicated code here, has no sense. > > I don't understand this comment, sorry. > > Regards, > Simon > Sorry for the misleading message. When I send this patch set, I forgot about adding the message-id of the previous thread as "in-reply-to". There was a discussion about insert the memory zeroing routines as an asm here, instead of using the 'memset' call. But I tested that there is no difference in the performance. So in this case, it's better to use the common lib and this commit is the same as it was in the first version. (I missed the changelog) Best regards, -- Przemyslaw Marczak Samsung R&D Institute Poland Samsung Electronics p.marczak at samsung.com