git: 84eaf2ccc6aa - x86: stop punishing VMs with low priority for TSC timecounter

[Konstantin Belousov]

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=84eaf2ccc6aa05da7b7389991d3023698b756e3f

commit 84eaf2ccc6aa05da7b7389991d3023698b756e3f
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2020-12-21 17:02:31 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2020-12-23 10:45:15 +0000

    x86: stop punishing VMs with low priority for TSC timecounter
    
    I suspect that virtualization techniques improved from the time when we
    have to effectively disable TSC use in VM.  For instance, it was reported
    (complained) in https://github.com/JuliaLang/julia/issues/38877 that
    FreeBSD is groundlessly slow on AWS with some loads.
    
    Remove the check and start watching for complaints.
    
    Reviewed by:    emaste, grehan
    Discussed with: cperciva
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D27629
---
 sys/x86/x86/tsc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c
index c8e9be0c3cd5..6b5242fb5d4f 100644
--- a/sys/x86/x86/tsc.c
+++ b/sys/x86/x86/tsc.c
@@ -499,7 +499,7 @@ test_tsc(int adj_max_count)
 	uint64_t *data, *tsc;
 	u_int i, size, adj;
 
-	if ((!smp_tsc && !tsc_is_invariant) || vm_guest)
+	if ((!smp_tsc && !tsc_is_invariant))
 		return (-100);
 	size = (mp_maxid + 1) * 3;
 	data = malloc(sizeof(*data) * size * N, M_TEMP, M_WAITOK);