Messages in this thread Patch in this message | | | Date | Tue, 11 Nov 2008 21:01:03 +0100 | From | Takashi Iwai <> | Subject | [PATCH] Allocate module.ref array dynamically |
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Hi,
we found that the kernel module sizes and memory footprints grow drastically when NR_CPUS is high. For example, with NR_CPUS=4096, SUSE kernel packages weigh over 500MB (even w/o debug info).
A part of the reason is the fixed size array in struct module. The patch below fixes the problem by allocating it dynamically. With the patch, the size can go down to 20MB.
Any comments/suggestions appreciated.
thanks,
Takashi
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From: Takashi Iwai <tiwai@suse.de> Subject: [PATCH] Allocate module.ref array dynamically
This patch makes the module handling code to allocate the ref array of each module struct dynamically. It saves both module disk space and memory footprints when number of CPUs is high like 4096.
Reference: Novell bnc#425240 https://bugzilla.novell.com/show_bug.cgi?id=425240
Signed-off-by: Takashi Iwai <tiwai@suse.de>
--- include/linux/module.h | 2 +- kernel/module.c | 21 ++++++++++++++++----- 2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c --- a/kernel/module.c +++ b/kernel/module.c @@ -559,17 +559,24 @@ static char last_unloaded_module[MODULE_ #ifdef CONFIG_MODULE_UNLOAD /* Init the unload section of the module. */ -static void module_unload_init(struct module *mod) +static int module_unload_init(struct module *mod) { unsigned int i; INIT_LIST_HEAD(&mod->modules_which_use_me); - for (i = 0; i < NR_CPUS; i++) + + mod->ref = kcalloc(nr_cpu_ids, sizeof(*mod->ref), GFP_KERNEL); + if (!mod->ref) + return -ENOMEM; + + for (i = 0; i < nr_cpu_ids; i++) local_set(&mod->ref[i].count, 0); /* Hold reference count during initialization. */ local_set(&mod->ref[raw_smp_processor_id()].count, 1); /* Backwards compatibility macros put refcount during init. */ mod->waiter = current; + + return 0; } /* modules using other modules */ @@ -649,6 +656,7 @@ static void module_unload_free(struct mo } } } + kfree(mod->ref); } #ifdef CONFIG_MODULE_FORCE_UNLOAD @@ -707,7 +715,7 @@ unsigned int module_refcount(struct modu { unsigned int i, total = 0; - for (i = 0; i < NR_CPUS; i++) + for (i = 0; i < nr_cpu_ids; i++) total += local_read(&mod->ref[i].count); return total; } @@ -896,8 +904,9 @@ static inline int use_module(struct modu return strong_try_module_get(b) == 0; } -static inline void module_unload_init(struct module *mod) +static inline int module_unload_init(struct module *mod) { + return 0; } #endif /* CONFIG_MODULE_UNLOAD */ @@ -2123,7 +2132,9 @@ static noinline struct module *load_modu mod = (void *)sechdrs[modindex].sh_addr; /* Now we've moved module, initialize linked lists, etc. */ - module_unload_init(mod); + err = module_unload_init(mod); + if (err) + goto free_unload; /* add kobject, so we can reference it. */ err = mod_sysfs_init(mod); diff --git a/include/linux/module.h b/include/linux/module.h --- a/include/linux/module.h +++ b/include/linux/module.h @@ -349,7 +349,7 @@ struct module void (*exit)(void); /* Reference counts */ - struct module_ref ref[NR_CPUS]; + struct module_ref *ref; #endif }; #ifndef MODULE_ARCH_INIT
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