On Mon, 10 Oct 2005, Yingchao Zhou wrote:
>
> The sys_swapon system call open the swap-file through
> filp_open(..., O_RDWR|O_LARGEFILE,...).
> In this way, I think that the pageout process of anonymous
> pages finally will write them out through (swap-file)->f_ops->write,
No, they are written out by swap_writepage. The opening in sys_swapon
gets a handle of what is to be used for swap, but it then goes its own way.
> and it will result in caches of swapfile. However, swapping only
> happens when memory is tight. So why not set O_DIRECT? Is there any
> special reason to keep caches of swapfile?
Caches of swapfile are useful (but yes, can be discarded when memory
is tight). There's nothing indirect about them: the page that is mapped
into userspace gets written to disk, the page that is read in from disk
gets mapped back into userspace.
Hugh
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
