Messages in this thread | | | Date | Mon, 24 Mar 2008 16:05:12 +0000 | From | "Will Newton" <> | Subject | Re: [PATCH 2/6] compcache: block device - internal defs |
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On Mon, Mar 24, 2008 at 3:03 PM, Nitin Gupta <nitingupta910@gmail.com> wrote:
Hi Nitin,
> This contains header to be used internally by block device code. > It contains flags to enable/disable debugging, stats collection and also > defines default disk size (25% of total RAM). > > Signed-off-by: Nitin Gupta <nitingupta910 at gmail dot com> > --- > drivers/block/compcache.h | 147 +++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 147 insertions(+), 0 deletions(-) > > diff --git a/drivers/block/compcache.h b/drivers/block/compcache.h > new file mode 100644 > index 0000000..b84b5d3 > --- /dev/null > +++ b/drivers/block/compcache.h > @@ -0,0 +1,147 @@ > +/* > + * Compressed RAM based swap device > + * > + * (C) Nitin Gupta > + * > + * This RAM based block device acts as swap disk. > + * Pages swapped to this device are compressed and > + * stored in memory. > + * > + * Project home: http://code.google.com/p/compcache > + */ > + > +#ifndef _COMPCACHE_H_ > +#define _COMPCACHE_H_ > + > +#define K(x) ((x) >> 10) > +#define KB(x) ((x) << 10) > + > +#define SECTOR_SHIFT 9 > +#define SECTOR_SIZE (1 << SECTOR_SHIFT) > +#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) > +#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) > + > +/*-- Configurable parameters */ > +/* Default compcache size: 25% of total RAM */ > +#define DEFAULT_COMPCACHE_PERCENT 25 > +#define INIT_SIZE KB(16) > +#define GROW_SIZE INIT_SIZE
Maybe these could be renamed to INIT_SIZE_BYTES/GROW_SIZE_BYTES to make the units clearer?
> +/*-- */ > + > +/* Message prefix */ > +#define C "compcache: " > + > +/* Debugging and Stats */ > +#define NOP do { } while(0) > + > +#if (1 || defined(CONFIG_DEBUG_COMPCACHE)) > +#define DEBUG 1 > +#define STATS 1 > +#else > +#define DEBUG 0 > +#define STATS 0 > +#endif
If DEBUG is defined unconditionally what is the point of CONFIG_DEBUG_COMPCACHE?
> + > +/* Create /proc/compcache? */ > +/* If STATS is disabled, this will give minimal compcache info */ > +#define CONFIG_COMPCACHE_PROC > + > +#if DEBUG > +#define CC_DEBUG(fmt,arg...) \ > + printk(KERN_DEBUG C fmt,##arg) > +#else > +#define CC_DEBUG(fmt,arg...) NOP > +#endif
Have you thought about using pr_debug() for this? It looks like it would simplify this file at the cost of a little flexibility.
> + > +/* > + * Verbose debugging: > + * Enable basic debugging + verbose messages spread all over code > + */ > +#define DEBUG2 0 > + > +#if DEBUG2 > +#define DEBUG 1 > +#define STATS 1 > +#define CONFIG_COMPCACHE_PROC 1 > +#define CC_DEBUG2((fmt,arg...) \ > + printk(KERN_DEBUG C fmt,##arg) > +#else /* DEBUG2 */ > +#define CC_DEBUG2(fmt,arg...) NOP > +#endif > + > +/* Its useless to collect stats if there is no way to export it */ > +#if (STATS && !defined(CONFIG_COMPCACHE_PROC)) > +#error "compcache stats is enabled but not /proc/compcache." > +#endif
So it appears that if we want DEBUG we also get STATS, which requires /proc support enabled, so it is impossible to have just DEBUG and no STATS or /proc support?
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