From mboxrd@z Thu Jan 1 00:00:00 1970 From: Przemyslaw Marczak Date: Wed, 28 Jan 2015 15:10:39 +0100 Subject: [U-Boot] [PATCH 0/3] arm: reduce .bss section clear time In-Reply-To: <54C8E024.8070504@denx.de> References: <1422449743-10119-1-git-send-email-p.marczak@samsung.com> <54C8E024.8070504@denx.de> Message-ID: <54C8EDDF.4090909@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 Stefan, On 01/28/2015 02:12 PM, Stefan Roese wrote: > Hi Przemyslaw, > > On 28.01.2015 13:55, Przemyslaw Marczak wrote: >> This patchset reduces the boot time for ARM architecture, >> Exynos boards, and boards with DFU enabled(ARM). >> >> For tested Trats2 device, this was done in three steps. >> >> First was enable the arch memcpy and memset. >> The second step was enable memset for .bss clear. >> The third step for reduce this operation is to keep .bss section >> small as possible. >> >> The .bss section will grow if we have a lot of static variables. >> This section is cleared before jump to the relocated U-Boot, >> and it's done word by word. To reduce the time for this step, >> we can enable arch memset, which uses multiple ARM registers. >> >> For configs with DFU enabled, we can find the dfu buffer in this section, >> which has at least 8MB (32MB for trats2). This is a lot of useless data, >> which is not required for standard boot. So this buffer should be dynamic >> allocated. >> >> Przemyslaw Marczak (3): >> exynos: config: enable arch memcpy and arch memset >> arm: relocation: clear .bss section with arch memset if defined >> dfu: mmc: file buffer: remove static allocation >> >> arch/arm/lib/crt0.S | 10 +++++++++- >> drivers/dfu/dfu_mmc.c | 25 ++++++++++++++++++++++--- >> include/configs/exynos-common.h | 3 +++ >> 3 files changed, 34 insertions(+), 4 deletions(-) > > Looking at the commit messages of this patchset I can conclude that your > overall boot time reduction is: > > from ~1527ms > to ~464ms > > This is amazing! Congrats. :) > Thank you. I was also amazed. The time results are taken with from the clock cycle counter, I think it's reliable. Some day I would like to check it using the oscilloscope. > We really should in general make more use of the optimized functions and > take care that the buffers (e.g. the DFU buffer in this case) are used > in a sane way. > > Thanks, > Stefan > > Yes you're right, I thought that Exynos config has enabled arch memcpy/set lib, before I checked this... Best regards, -- Przemyslaw Marczak Samsung R&D Institute Poland Samsung Electronics p.marczak at samsung.com