> From: Seth Jennings [mailto:sjenning@xxxxxxxxxxxxxxxxxx] > Subject: Re: [PATCH 2/5] mm: frontswap: lazy initialization to allow tmem backends to build/run as > modules > > > static int __init init_frontswap(void) > > { > > + int i; > > #ifdef CONFIG_DEBUG_FS > > struct dentry *root = debugfs_create_dir("frontswap", NULL); > > if (root == NULL) > > @@ -364,6 +414,10 @@ static int __init init_frontswap(void) > > debugfs_create_u64("invalidates", S_IRUGO, > > root, &frontswap_invalidates); > > #endif > > + for (i = 0; i < MAX_INITIALIZABLE_SD; i++) > > + sds[i] = -1; > > + > > + frontswap_enabled = 1; > > If frontswap_enabled is going to be on all the time, then what point > does it serve? By extension, can all of the static inline wrappers in > frontswap.h be done away with? The intent of frontswap_enabled and cleancache_enabled was to avoid the overhead of a function call at the point where each frontswap/cleancache "hooks" is placed, using a global variable check instead. I'm not sure if this minor performance tuning effort is worth preserving: If not, I agree frontswap_enabled and the static inline wrappers (as well as their cleancache brethren) could be done away with **; if worth preserving, then I think frontswap_enabled could be set in the init method instead but the check for enabled in the frontswap init method and the cleancache init_fs method would need to be removed else lazy initialization wouldn't work. Dan ** Note to anyone that tries this: There is a subtle but clever hack in the wrappers suggested by Jeremy Fitzhardinge that disables the wrappers at compile-time as well as runtime. IOW, make sure you test-compile both with CONFIG_{CLEANCACHE|FRONTSWAP} _and_ with them unconfig'd. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
