Re: [PATCH] [46/48] Suspend2 2.1.9.8 for 2.6.12: 622-swapwriter.patch

Nigel Cunningham
2005-07-07T12:44:19Z

Hi.

On Wed, 2005-07-06 at 16:33, Pekka Enberg wrote:
> On 7/6/05, Nigel Cunningham <nigel@suspend2.net> wrote:
> > diff -ruNp 623-generic-block-io.patch-old/kernel/power/suspend_block_io.c 623-generic-block-io.patch-new/kernel/power/suspend_block_io.c
> > --- 623-generic-block-io.patch-old/kernel/power/suspend_block_io.c 1970-01-01 10:00:00.000000000 +1000
> > +++ 623-generic-block-io.patch-new/kernel/power/suspend_block_io.c 2005-07-05 23:48:59.000000000 +1000
> > @@ -0,0 +1,817 @@
> > +#include "suspend2_core/suspend.h"
> > +#include "suspend2_core/proc.h"
> > +#include "suspend2_core/plugins.h"
> > +#include "suspend2_core/utility.h"
> > +#include "suspend2_core/prepare_image.h"
>
> You've got circular dependencies. kernel/power/suspend2_core depends
> on kernel/power and vice versa. Please just consider putting them all
> in kernel/power/

Done. They were separate just to keep things tidy.

> > +/* Bits in struct io_info->flags */
> > +#define IO_WRITING 1
> > +#define IO_RESTORE_PAGE_PROT 2
> > +#define IO_AWAITING_READ 3
> > +#define IO_AWAITING_WRITE 4
> > +#define IO_AWAITING_SUBMIT 5
> > +#define IO_AWAITING_CLEANUP 6
> > +#define IO_HANDLE_PAGE_PROT 7
>
> Please use enums instead.

Done!

> > +
> > +#define MAX_OUTSTANDING_IO 1024
> > +
> > +/*
> > + * ---------------------------------------------------------------
> > + *
> > + * IO in progress information storage and helpers
> > + *
> > + * ---------------------------------------------------------------
> > + */
>
> Could we please drop the above banner. Hurts my eyes...

Sorry! :>

> > +
> > +struct io_info {
> > + struct bio * sys_struct;
> > + long block[PAGE_SIZE/512];
>
> You're hardcoding sector size here, no?

As others do.

> > + struct page * buffer_page;
> > + struct page * data_page;
> > + unsigned long flags;
> > + struct block_device * dev;
> > + struct list_head list;
> > + int readahead_index;
> > + struct work_struct work;
> > +};
> > +
> > +/* Locks separated to allow better SMP support.
> > + * An io_struct moves through the lists as follows.
> > + * free -> submit_batch -> busy -> ready_for_cleanup -> free
> > + */
> > +static LIST_HEAD(ioinfo_free);
> > +static spinlock_t ioinfo_free_lock = SPIN_LOCK_UNLOCKED;
>
> Please use DEFINE_SPINLOCK instead. It is preferred as some automatic
> lock checkers need it.

Done.

> > +#define BITS_PER_UL (8 * sizeof(unsigned long))
> > +static volatile unsigned long suspend_readahead_flags[(MAX_READAHEAD + BITS_PER_UL - 1) / BITS_PER_UL];
>
> <asm/types.h> has BITS_PER_LONG. Use it.

Thanks for educating the ignorant :>

> > +static int suspend_end_bio(struct bio * bio, unsigned int num, int err)
> > +{
> > + struct io_info *io_info = (struct io_info *) bio->bi_private;
>
> Redundant cast.

k.

> > +static unsigned long suspend_bio_memory_needed(void)
> > +{
> > + /* We want to have at least enough memory so as to have 128 I/O
> > + * transactions on the fly at once. If we can to more, fine. */
> > + return (128 * (PAGE_SIZE + sizeof(struct request) +
> > + sizeof(struct bio) + sizeof(struct io_info)));
>
> Where did the magic 128 come from?

My bad. Should be MAX_OUTSTANDING_IO.

Thanks, once again!

Nigel

--
Evolution.
Enumerate the requirements.
Consider the interdependencies.
Calculate the probabilities.
Be amazed that people believe it happened.