Re: [PATCH v6 12/12] FIT: add support to cache opened fit images

[Marco Felsch <m.felsch@pengutronix.de>]

On 25-08-20, Marco Felsch wrote:
> Hi,
> 
> On 25-08-20, Ahmad Fatoum wrote:
> > Hi,
> > 
> > On 8/20/25 11:48, Marco Felsch wrote:
> > > Cache the FIT image fit_open() calls to avoid loading the same FIT image
> > > twice. This is very useful if the same FIT image is used to provide the
> > > base devicetree, kernel and initrd as well as devicetree overlays.
> > 
> > Just curious, how much time does this save?
> 
> This depends on the amount of overlays you're going to check/apply. But
> in my use-case it reduced the time from ~1sec to 200ms for ~10 overlays
> which are stored together with the boot image e.g. kernel, base-dt,
> initrd.

Sorry I remembered incorrectly. In the end it does not depend on the
overlays but on the FIT which supplies the overlays and the boot-image.

IIRC, we reduced the FIT load time from 1sec to 200ms because the same
FIT is used for the overlays and the boot-image, so we only need to
fit_open() the image once.

Before the caching we had to open it twice:
 - 1nd time for the bootm bootm-image handling,
 - 2st time for the overlay handling.

Regards,
  Marco


> 
> Regards,
>   Marco
> 
> > 
> > Cheers,
> > Ahmad
> > 
> > > 
> > > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > > ---
> > >  common/image-fit.c  | 32 ++++++++++++++++++++++++++++++++
> > >  include/image-fit.h |  4 ++++
> > >  2 files changed, 36 insertions(+)
> > > 
> > > diff --git a/common/image-fit.c b/common/image-fit.c
> > > index c9d08d25f723665e5203d8e8372255a39bf739de..2cde844e46a61f412a46c2c7bb79d833153e5344 100644
> > > --- a/common/image-fit.c
> > > +++ b/common/image-fit.c
> > > @@ -16,6 +16,7 @@
> > >  #include <fs.h>
> > >  #include <malloc.h>
> > >  #include <linux/ctype.h>
> > > +#include <linux/refcount.h>
> > >  #include <asm/byteorder.h>
> > >  #include <errno.h>
> > >  #include <linux/err.h>
> > > @@ -33,6 +34,8 @@
> > >  #define CHECK_LEVEL_SIG 2
> > >  #define CHECK_LEVEL_MAX 3
> > >  
> > > +static LIST_HEAD(open_fits);
> > > +
> > >  static uint32_t dt_struct_advance(struct fdt_header *f, uint32_t dt, int size)
> > >  {
> > >  	dt += size;
> > > @@ -902,6 +905,18 @@ void *fit_open_configuration(struct fit_handle *handle, const char *name,
> > >  	return conf_node;
> > >  }
> > >  
> > > +static struct fit_handle *fit_get_handle(const char *filename)
> > > +{
> > > +	struct fit_handle *handle;
> > > +
> > > +	list_for_each_entry(handle, &open_fits, entry) {
> > > +		if (!strcmp(filename, handle->filename))
> > > +			return handle;
> > > +	}
> > > +
> > > +	return NULL;
> > > +}
> > > +
> > >  static int fit_do_open(struct fit_handle *handle)
> > >  {
> > >  	const char *desc = "(no description)";
> > > @@ -951,6 +966,8 @@ struct fit_handle *fit_open_buf(const void *buf, size_t size, bool verbose,
> > >  	handle->size = size;
> > >  	handle->verify = verify;
> > >  
> > > +	refcount_set(&handle->users, 1);
> > > +
> > >  	ret = fit_do_open(handle);
> > >  	if (ret) {
> > >  		fit_close(handle);
> > > @@ -985,6 +1002,12 @@ struct fit_handle *fit_open(const char *_filename, bool verbose,
> > >  		return ERR_PTR(-errno);
> > >  	}
> > >  
> > > +	handle = fit_get_handle(filename);
> > > +	if (handle) {
> > > +		refcount_inc(&handle->users);
> > > +		return handle;
> > > +	}
> > > +
> > >  	handle = xzalloc(sizeof(struct fit_handle));
> > >  
> > >  	handle->verbose = verbose;
> > > @@ -1002,6 +1025,9 @@ struct fit_handle *fit_open(const char *_filename, bool verbose,
> > >  	handle->fit = handle->fit_alloc;
> > >  	handle->filename = filename;
> > >  
> > > +	refcount_set(&handle->users, 1);
> > > +	list_add(&handle->entry, &open_fits);
> > > +
> > >  	ret = fit_do_open(handle);
> > >  	if (ret) {
> > >  		fit_close(handle);
> > > @@ -1013,9 +1039,15 @@ struct fit_handle *fit_open(const char *_filename, bool verbose,
> > >  
> > >  static void __fit_close(struct fit_handle *handle)
> > >  {
> > > +	if (!refcount_dec_and_test(&handle->users))
> > > +		return;
> > > +
> > >  	if (handle->root)
> > >  		of_delete_node(handle->root);
> > >  
> > > +	if (handle->filename)
> > > +		list_del(&handle->entry);
> > > +
> > >  	free(handle->filename);
> > >  	free(handle->fit_alloc);
> > >  }
> > > diff --git a/include/image-fit.h b/include/image-fit.h
> > > index 68f70f4365cb7a650596263086f7de2209d5957e..f9791ff251c554eda56bf3af98c8abceb056a176 100644
> > > --- a/include/image-fit.h
> > > +++ b/include/image-fit.h
> > > @@ -7,6 +7,7 @@
> > >  #define __IMAGE_FIT_H__
> > >  
> > >  #include <linux/types.h>
> > > +#include <linux/refcount.h>
> > >  #include <bootm.h>
> > >  
> > >  struct fit_handle {
> > > @@ -15,6 +16,9 @@ struct fit_handle {
> > >  	size_t size;
> > >  	char *filename;
> > >  
> > > +	struct list_head entry;
> > > +	refcount_t users;
> > > +
> > >  	bool verbose;
> > >  	enum bootm_verify verify;
> > >  
> > > 
> > 
> > -- 
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> > 
> > 
> 
>