I am continuing some experiments in booting Linux w/ a flattened device tree via u-boot (1.3.2-rc3) from JFFS2 on NAND on an AMCC "Haleakala" board and am curious if anyone has come up with some quantitative performance characterizations of the various options (in all cases, u-boot lives on NOR flash). The options I am evaluating are:
1) Put uImage and haleakala.dtb in their own "raw" NAND slices and boot with u-boot nand commands: static struct mtd_partition nand_parts[] = { { .name = "kernel", .offset = 0, .size = 0x0400000 }, { .name = "fdt", .offset = 0x0400000, .size = 0x0010000 }, { .name = "root", .offset = 0x0410000, .size = 0x3BF0000 } }; => nand read.i 200000 0 400000 => nand read.i 400000 400000 10000 => setenv bootargs ${bootargs} console=ttyS0,${baudrate} => setenv bootargs ${bootargs} root=/dev/mtdblock9 rootfstype=jffs2 => bootm 200000 - 400000 Qualitative performance: Nearly instantaneous. As expected, in this case the qualitative, subjective time to seeing "Linux version 2.6.25-rc3-00951-g6514352-dirty ..." is nearly instantaneous. 2) Put uImage and haleakala.dtb as files in /boot in the ~12 MB JFFS2 root file system image in the ~60 MB "root" NAND slice and boot with u-boot fsload commands: => fsload 200000 boot/uImage => fsload 400000 boot/haleakala.dtb => setenv bootargs ${bootargs} console=ttyS0,${baudrate} => setenv bootargs ${bootargs} root=/dev/mtdblock9 rootfstype=jffs2 => bootm 200000 - 400000 2a) With CFG_JFFS2_SORT_FRAGMENTS enabled. Qualitative performance: Takes the better part of 30-35 minutes. As expected with the in-documentation warnings about CFG_JFFS2_SORT_FRAGMENTS and looking at the code in u-boot/fs/jffs2/jffs2_nand_1pass.c, the qualitative, subjective time to seeing the Linux version banner is slow, slow and slow. 2b) With CFG_JFFS2_SORT_FRAGMENTS disabled. Qualitative performance: Takes about 30 seconds to two minutes. 3) This is a hybrid approach that I am setting up right now and is where I am curious if anyone has done plots of fsload time on JFFS2 + NAND relative to file system size. Here, we use a separate 4 MB "/boot" JFFS2 file system for uImage and haleakala.dtb files and a 60 MB "/" JFFS2 file system for the root file system. static struct mtd_partition nand_parts[] = { { .name = "boot", .offset = 0, .size = 0x0400000 }, { .name = "root", .offset = 0x0400000, .size = 0x3C00000 } }; => fsload 200000 uImage => fsload 400000 haleakala.dtb => setenv bootargs ${bootargs} console=ttyS0,${baudrate} => setenv bootargs ${bootargs} root=/dev/mtdblock9 rootfstype=jffs2 => bootm 200000 - 400000 3a) With CFG_JFFS2_SORT_FRAGMENTS enabled. Shouldn't be necessary since the /boot file system would only ever be accessed read-only and updated by nandwrite, not individual file updates. 3b) With CFG_JFFS2_SORT_FRAGMENTS disabled. Qualitative performance: TBD <= 2b Thanks, Grant Erickson _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded