Re: ext4 not currently doing (much) multi-block allocation?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Sun, Feb 15, 2009 at 08:36:18AM -0500, Theodore Tso wrote:
> On Sun, Feb 15, 2009 at 04:35:28PM +0530, Aneesh Kumar K.V wrote:
> > Here is how it works. During writepages we loop through the dirty pages
> > and build largest contiguous block extent (mpage_add_bh_to_extent). Then we call
> > mpage_da_map_blocks. mpage_da_map_blocks does the mutli block request.
> > Once we have the blocks allocated we map these blocks to the pages. And
> > then we writeback one page at a time using writepage callback.
> 
> mpage_da_map_blocks() calls mpd->get_block, which is set to
> ext4_da_get_block_write(), which allocates a single block at a time
> (max_blocks is set to bh->b_size >> inode->i_blkbits).


That bh>b_size indicate multiple blocks. 

we do the below in mpage_add_bh_to_extent

2024         if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
2025                 lbh->b_size += b_size;
2026                 return;
2027         }

> 
> Put another way, where is the call to ext4_get_blocks_wrap() which
> does the multi-block request?  I don't see it...
> 

-aneesh
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Reiser Filesystem Development]     [Ceph FS]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite National Park]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]     [Linux Media]

  Powered by Linux