Date: Wed, 30 Dec 2020 22:45:53 GMT From: Piotr Kubaj <pkubaj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 6260bfb08742 - main - powerpc: Optimize copyinstr() to avoid repeatedly mapping user strings Message-ID: <202012302245.0BUMjrQN032417@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch main has been updated by pkubaj (ports committer): URL: https://cgit.FreeBSD.org/src/commit/?id=6260bfb0874280d3fb58ac52699e2aee6ecca8a8 commit 6260bfb0874280d3fb58ac52699e2aee6ecca8a8 Author: Justin Hibbits <chmeeedalf@gmail.com> AuthorDate: 2020-06-04 18:15:15 +0000 Commit: Piotr Kubaj <pkubaj@FreeBSD.org> CommitDate: 2020-12-30 22:45:35 +0000 powerpc: Optimize copyinstr() to avoid repeatedly mapping user strings Currently copyinstr() uses fubyte() to read each byte from userspace. However, this means that for each byte, it calls pmap_map_user_ptr() to map the string into memory. This is needlessly wasteful, since the string will rarely ever cross a segment boundary. Instead, map a segment at a time, and copy as much from that segment as possible at a time. Measured with the HPT pmap on powerpc64, this saves roughly 8% time on buildkernel, and 5% on buildworld, in wallclock time. --- sys/powerpc/powerpc/copyinout.c | 46 +++++++++++++++++++++++++++++------------ 1 file changed, 33 insertions(+), 13 deletions(-) diff --git a/sys/powerpc/powerpc/copyinout.c b/sys/powerpc/powerpc/copyinout.c index 76965ad996b8..1528accc0e0e 100644 --- a/sys/powerpc/powerpc/copyinout.c +++ b/sys/powerpc/powerpc/copyinout.c @@ -236,31 +236,51 @@ REMAP(copyin)(const void *udaddr, void *kaddr, size_t len) int REMAP(copyinstr)(const void *udaddr, void *kaddr, size_t len, size_t *done) { + struct thread *td; + pmap_t pm; + jmp_buf env; const char *up; - char *kp; - size_t l; - int rv, c; + char *kp, *p; + size_t i, l, t; + int rv; - kp = kaddr; - up = udaddr; + td = curthread; + pm = &td->td_proc->p_vmspace->vm_pmap; + t = 0; rv = ENAMETOOLONG; - for (l = 0; len-- > 0; l++) { - if ((c = fubyte(up++)) < 0) { + td->td_pcb->pcb_onfault = &env; + if (setjmp(env)) { + rv = EFAULT; + goto done; + } + + kp = kaddr; + up = udaddr; + + while (len > 0) { + if (pmap_map_user_ptr(pm, up, (void **)&p, len, &l)) { rv = EFAULT; - break; + goto done; } - if (!(*kp++ = c)) { - l++; - rv = 0; - break; + for (i = 0; len > 0 && i < l; i++, t++, len--) { + if ((*kp++ = *p++) == 0) { + i++, t++; + rv = 0; + goto done; + } } + + up += l; } +done: + td->td_pcb->pcb_onfault = NULL; + if (done != NULL) { - *done = l; + *done = t; } return (rv);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202012302245.0BUMjrQN032417>