diff mbox series

[1/4] proc/kcore: mark proc entry as permanent

Message ID 60873e6afcfda3f08d0456f19e4733612afcf134.1731115587.git.osandov@fb.com (mailing list archive)
State New
Headers show
Series proc/kcore: performance optimizations | expand

Commit Message

Omar Sandoval Nov. 9, 2024, 1:28 a.m. UTC 
From: Omar Sandoval <osandov@fb.com>

drgn reads from /proc/kcore to debug the running kernel. For many drgn
scripts, /proc/kcore is actually a bottleneck.

use_pde() and unuse_pde() in prog_reg_read() show up hot in profiles.
Since the entry for /proc/kcore can never be removed, this is useless
overhead that can be trivially avoided by marking the entry as
permanent.

In my benchmark, this reduces the time per read by about 20 nanoseconds,
from 235 nanoseconds per read to 215.

Link: https://github.com/osandov/drgn/issues/106
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/proc/kcore.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 51446c59388f..770e4e57f445 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -662,6 +662,7 @@  static int release_kcore(struct inode *inode, struct file *file)
 }
 
 static const struct proc_ops kcore_proc_ops = {
+	.proc_flags	= PROC_ENTRY_PERMANENT,
 	.proc_read_iter	= read_kcore_iter,
 	.proc_open	= open_kcore,
 	.proc_release	= release_kcore,