| Message ID | 1311599243-875-1-git-send-email-hrishikesh.b@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 25, 2011 at 06:37:23PM +0530, Hrishikesh Bhandiwad wrote: > In the nand partition table specifying the offset addresses > directly instead of using the macro MTDPART_OFS_APPEND to gain > runtime efficiency while nand initialization. > MTDPART_OFS_APPEND has the value (-1) ,if assigned to offset, > a runtime calculation of actual offset happens each time nand is > initialized [ Refer: drivers/mtd/mtdpart.c: allocate_partition()]. > To avoid this , specify actual offset. > > Signed-off-by: Hrishikesh Bhandiwad <hrishikesh.b@ti.com> did you measure any significant gains when doing this ? Also, why only beagle ? why not all boards already ? Measurment data of how long it takes for the runtime calculation of the offset to complete would be nice to see.
Hi again, On Mon, Jul 25, 2011 at 04:14:06PM +0300, Felipe Balbi wrote: > On Mon, Jul 25, 2011 at 06:37:23PM +0530, Hrishikesh Bhandiwad wrote: > > In the nand partition table specifying the offset addresses > > directly instead of using the macro MTDPART_OFS_APPEND to gain > > runtime efficiency while nand initialization. > > MTDPART_OFS_APPEND has the value (-1) ,if assigned to offset, > > a runtime calculation of actual offset happens each time nand is > > initialized [ Refer: drivers/mtd/mtdpart.c: allocate_partition()]. > > To avoid this , specify actual offset. > > > > Signed-off-by: Hrishikesh Bhandiwad <hrishikesh.b@ti.com> > > did you measure any significant gains when doing this ? Also, why only > beagle ? why not all boards already ? Measurment data of how long it > takes for the runtime calculation of the offset to complete would be > nice to see. I was just looking at the code and the offset calculation will always be done regardless of you using the direct offset or the MTDPART_OFS_APEND. The only thing you avoid by setting it directly is a branch. See here: 648 int add_mtd_partitions(struct mtd_info *master, 649 const struct mtd_partition *parts, 650 int nbparts) 651 { 652 struct mtd_part *slave; 653 uint64_t cur_offset = 0; 654 int i; 655 656 printk(KERN_NOTICE "Creating %d MTD partitions on \"%s\":\n", nbparts, master->name); 657 658 for (i = 0; i < nbparts; i++) { 659 slave = allocate_partition(master, parts + i, i, cur_offset); 660 if (IS_ERR(slave)) 661 return PTR_ERR(slave); 662 663 mutex_lock(&mtd_partitions_mutex); 664 list_add(&slave->list, &mtd_partitions); 665 mutex_unlock(&mtd_partitions_mutex); 666 667 add_mtd_device(&slave->mtd); 668 669 cur_offset = slave->offset + slave->mtd.size; 670 } 671 672 return 0; 673 } regardless of you passing MTDPART_OFS_APEND or direct slave->offset, cur_ofsset will be calculated, and that thing looks really cheap to execute to me. The only thing you're avoid is: 467 slave->offset = part->offset; 468 469 if (slave->offset == MTDPART_OFS_APPEND) 470 slave->offset = cur_offset; the if at line 469. Am I missing something ??
diff --git a/arch/arm/mach-omap2/board-omap3beagle.c b/arch/arm/mach-omap2/board-omap3beagle.c index 7f21d24..09f7571 100644 --- a/arch/arm/mach-omap2/board-omap3beagle.c +++ b/arch/arm/mach-omap2/board-omap3beagle.c @@ -140,23 +140,23 @@ static struct mtd_partition omap3beagle_nand_partitions[] = { }, { .name = "U-Boot", - .offset = MTDPART_OFS_APPEND, /* Offset = 0x80000 */ + .offset = 0x80000 .size = 15 * NAND_BLOCK_SIZE, .mask_flags = MTD_WRITEABLE, /* force read-only */ }, { .name = "U-Boot Env", - .offset = MTDPART_OFS_APPEND, /* Offset = 0x260000 */ + .offset = 0x260000 .size = 1 * NAND_BLOCK_SIZE, }, { .name = "Kernel", - .offset = MTDPART_OFS_APPEND, /* Offset = 0x280000 */ + .offset = 0x280000 .size = 32 * NAND_BLOCK_SIZE, }, { .name = "File System", - .offset = MTDPART_OFS_APPEND, /* Offset = 0x680000 */ + .offset = 0x680000 .size = MTDPART_SIZ_FULL, }, };
In the nand partition table specifying the offset addresses directly instead of using the macro MTDPART_OFS_APPEND to gain runtime efficiency while nand initialization. MTDPART_OFS_APPEND has the value (-1) ,if assigned to offset, a runtime calculation of actual offset happens each time nand is initialized [ Refer: drivers/mtd/mtdpart.c: allocate_partition()]. To avoid this , specify actual offset. Signed-off-by: Hrishikesh Bhandiwad <hrishikesh.b@ti.com> --- arch/arm/mach-omap2/board-omap3beagle.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-)