On Thu, 16 Oct 2014 09:24:01 -0700 Casey Schaufler <[email protected]> wrote:
> On 10/15/2014 5:10 AM, Rohit wrote: > > The patch use kmem_cache to allocate/free inode_smack since they are > > alloced in high volumes making it a perfect case for kmem_cache. > > > > As per analysis, 24 bytes of memory is wasted per allocation due > > to internal fragmentation. With kmem_cache, this can be avoided. > > What impact does this have on performance? I am much more > concerned with speed than with small amount of memory. > I think there should not be any performance problem as such. However, please let me know how to check the performance in this case. As far as i know, kzalloc first finds the kmalloc_index corresponding to the size to get the kmem_cache_object and then calls kmem_cache_alloc with the kmalloc_index(kmem_cache object). Here, we create kmem_cache object specific for inode_smack and directly calls kmem_cache_alloc() which should give better performance as compared to kzalloc. Please let me know your comments. > > > > Accounting of memory allocation is below : > > total slack net count-alloc/free > > caller Before (with kzalloc) > > 1919872 719952 1919872 29998/0 > > new_inode_smack+0x14 > > > > After (with kmem_cache) > > 1201680 0 1201680 30042/0 > > new_inode_smack+0x18 > > > > >From above data, we found that 719952 bytes(~700 KB) of memory is > > saved on allocation of 29998 smack inodes. > > > > Signed-off-by: Rohit <[email protected]> > > --- > > Added static in kmem_cache object declaration noted by Andrew > > Morton <akpm@ linux-foundation.org> . Also updated commit message. > > security/smack/smack_lsm.c | 13 ++++++++++--- > > 1 file changed, 10 insertions(+), 3 deletions(-) > > > > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c > > index d515ec2..15d985c 100644 > > --- a/security/smack/smack_lsm.c > > +++ b/security/smack/smack_lsm.c > > @@ -53,6 +53,7 @@ > > #define SMK_SENDING 2 > > > > LIST_HEAD(smk_ipv6_port_list); > > +static struct kmem_cache *smack_inode_cache; > > > > #ifdef CONFIG_SECURITY_SMACK_BRINGUP > > static void smk_bu_mode(int mode, char *s) > > @@ -240,7 +241,7 @@ struct inode_smack *new_inode_smack(struct > > smack_known *skp) { > > struct inode_smack *isp; > > > > - isp = kzalloc(sizeof(struct inode_smack), GFP_NOFS); > > + isp = kmem_cache_zalloc(smack_inode_cache, GFP_NOFS); > > if (isp == NULL) > > return NULL; > > > > @@ -767,7 +768,7 @@ static int smack_inode_alloc_security(struct > > inode *inode) */ > > static void smack_inode_free_security(struct inode *inode) > > { > > - kfree(inode->i_security); > > + kmem_cache_free(smack_inode_cache, inode->i_security); > > inode->i_security = NULL; > > } > > > > @@ -4264,10 +4265,16 @@ static __init int smack_init(void) > > if (!security_module_enable(&smack_ops)) > > return 0; > > > > + smack_inode_cache = KMEM_CACHE(inode_smack, 0); > > + if (!smack_inode_cache) > > + return -ENOMEM; > > + > > tsp = new_task_smack(&smack_known_floor, > > &smack_known_floor, GFP_KERNEL); > > - if (tsp == NULL) > > + if (tsp == NULL) { > > + kmem_cache_destroy(smack_inode_cache); > > return -ENOMEM; > > + } > > > > printk(KERN_INFO "Smack: Initializing.\n"); > > > Thanks, Rohit -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
