From d9da70c7c6230b9698dc4a1dbc4d7f05794d2740 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 3 Aug 2022 12:42:52 +0200
Subject: kernel: reuse a single allocation for all vfs_requests of a process

$ iostress 32 512 0 > /vtty # before
512 calls, 0 bytes. avg 121133
$ iostress 32 512 0 > /vtty # after
512 calls, 0 bytes. avg 103540

103540/121133 = ~85%

I think the tiny bit of added complexity is worth it here.
---
 src/kernel/proc.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src/kernel/proc.h')

diff --git a/src/kernel/proc.h b/src/kernel/proc.h
index c7e885a..d6f84bd 100644
--- a/src/kernel/proc.h
+++ b/src/kernel/proc.h
@@ -35,9 +35,6 @@ struct process {
 	// saved value, meaning depends on .state
 	union {
 		int death_msg; // PS_DEAD
-		struct {
-			struct vfs_request *req;
-		} waits4fs; // PS_WAITS4FS
 		struct {
 			char __user *buf;
 			size_t max_len;
@@ -52,6 +49,9 @@ struct process {
 	};
 	struct vfs_request *handled_req;
 
+	/* allocated once, the requests from WAITS4FS get stored here */
+	struct vfs_request *reqslot;
+
 	/* vfs_backend controlled (not exclusively) by this process */
 	struct vfs_backend *controlled;
 
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