Messages in this thread | | | Date | Thu, 31 Aug 2023 19:54:26 -0700 | Subject | Re: [PATCH -next] RFC: apparmor: Optimize retrieving current task secid | From | John Johansen <> |
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On 8/31/23 19:45, Vinicius Costa Gomes wrote: > John Johansen <john.johansen@canonical.com> writes: > >> On 8/31/23 16:22, Vinicius Costa Gomes wrote: >>> When running will-it-scale[1] open2_process testcase, in a system with a >>> large number of cores, a bottleneck in retrieving the current task >>> secid was detected: >>> >>> 27.73% ima_file_check;do_open (inlined);path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_x64 (inlined);do_syscall_64;entry_SYSCALL_64_after_hwframe (inlined);__libc_open64 (inlined) >>> 27.72% 0.01% [kernel.vmlinux] [k] security_current_getsecid_subj - - >>> 27.71% security_current_getsecid_subj;ima_file_check;do_open (inlined);path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_x64 (inlined);do_syscall_64;entry_SYSCALL_64_after_hwframe (inlined);__libc_open64 (inlined) >>> 27.71% 27.68% [kernel.vmlinux] [k] apparmor_current_getsecid_subj - - >>> 19.94% __refcount_add (inlined);__refcount_inc (inlined);refcount_inc (inlined);kref_get (inlined);aa_get_label (inlined);aa_get_label (inlined);aa_get_current_label (inlined);apparmor_current_getsecid_subj;security_current_getsecid_subj;ima_file_check;do_open (inlined);path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_x64 (inlined);do_syscall_64;entry_SYSCALL_64_after_hwframe (inlined);__libc_open64 (inlined) >>> 7.72% __refcount_sub_and_test (inlined);__refcount_dec_and_test (inlined);refcount_dec_and_test (inlined);kref_put (inlined);aa_put_label (inlined);aa_put_label (inlined);apparmor_current_getsecid_subj;security_current_getsecid_subj;ima_file_check;do_open (inlined);path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_x64 (inlined);do_syscall_64;entry_SYSCALL_64_after_hwframe (inlined);__libc_open64 (inlined) >>> >>> A large amount of time was spent in the refcount. >>> >>> The most common case is that the current task label is available, and >>> no need to take references for that one. That is exactly what the >>> critical section helpers do, make use of them. >>> >>> New perf output: >>> >>> 39.12% vfs_open;path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_64;entry_SYSCALL_64_after_hwframe;__libc_open64 (inlined) >>> 39.07% 0.13% [kernel.vmlinux] [k] do_dentry_open - - >>> 39.05% do_dentry_open;vfs_open;path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_64;entry_SYSCALL_64_after_hwframe;__libc_open64 (inlined) >>> 38.71% 0.01% [kernel.vmlinux] [k] security_file_open - - >>> 38.70% security_file_open;do_dentry_open;vfs_open;path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_64;entry_SYSCALL_64_after_hwframe;__libc_open64 (inlined) >>> 38.65% 38.60% [kernel.vmlinux] [k] apparmor_file_open - - >>> 38.65% apparmor_file_open;security_file_open;do_dentry_open;vfs_open;path_openat;do_filp_open;do_sys_openat2;__x64_sys_openat;do_syscall_64;entry_SYSCALL_64_after_hwframe;__libc_open64 (inlined) >>> >>> The result is a throughput improvement of around 20% across the board >>> on the open2 testcase. On more realistic workloads the impact should >>> be much less. >>> hrmmm, interesting. its a nice improvement >> >>> [1] https://github.com/antonblanchard/will-it-scale >>> >>> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> >> >> Acked-by: John Johansen <john.johansen@canonical.com> >> >> do you want me to pull this into apparmor-next or do you have another >> tree in mind >> > > -next is fine. > >>> --- >>> Sending as RFC because I am not sure there's anything I am missing. My >>> read of the code tells me it should be fine. >> >> it is >> > > Great. Do you want me to send a non-RFC version? > you can if you want but there is no need, I can do that small edit
>>> >>> security/apparmor/lsm.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c >>> index 108eccc5ada5..98e65c44ddd5 100644 >>> --- a/security/apparmor/lsm.c >>> +++ b/security/apparmor/lsm.c >>> @@ -766,9 +766,9 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm) >>> >>> static void apparmor_current_getsecid_subj(u32 *secid) >>> { >>> - struct aa_label *label = aa_get_current_label(); >>> + struct aa_label *label = __begin_current_label_crit_section(); >>> *secid = label->secid; >>> - aa_put_label(label); >>> + __end_current_label_crit_section(label); >>> } >>> >>> static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid) >> > > Cheers,
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