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Linux 4.14, 4.19, 5.0+ compat: SIMD save/restore

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Contrary to initial testing we cannot rely on these kernels to
invalidate the per-cpu FPU state and restore the FPU registers.
Nor can we guarantee that the kernel won't modify the FPU state
which we saved in the task struck.

Therefore, the kfpu_begin() and kfpu_end() functions have been
updated to save and restore the FPU state using our own dedicated
per-cpu FPU state variables.

This has the additional advantage of allowing us to use the FPU
again in user threads.  So we remove the code which was added to
use task queues to ensure some functions ran in kernel threads.

Reviewed-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #9346
Closes #9403
This commit is contained in:
Brian Behlendorf
2019-10-24 10:17:33 -07:00
committed by GitHub
parent b834b58ae6
commit 10fa254539
19 changed files with 276 additions and 294 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zcommon/zfs_fletcher.c
+4 -16
View File
@@ -726,7 +726,7 @@ fletcher_4_benchmark_impl(boolean_t native, char *data, uint64_t data_size)
* Initialize and benchmark all supported implementations.
*/
static void
fletcher_4_benchmark(void *arg)
fletcher_4_benchmark(void)
{
fletcher_4_ops_t *curr_impl;
int i, c;
@@ -769,20 +769,10 @@ fletcher_4_benchmark(void *arg)
void
fletcher_4_init(void)
{
#if defined(_KERNEL)
/*
* For 5.0 and latter Linux kernels the fletcher 4 benchmarks are
* run in a kernel threads. This is needed to take advantage of the
* SIMD functionality, see linux/simd_x86.h for details.
*/
taskqid_t id = taskq_dispatch(system_taskq, fletcher_4_benchmark,
NULL, TQ_SLEEP);
if (id != TASKQID_INVALID) {
taskq_wait_id(system_taskq, id);
} else {
fletcher_4_benchmark(NULL);
}
/* Determine the fastest available implementation. */
fletcher_4_benchmark();
#if defined(_KERNEL)
/* Install kstats for all implementations */
fletcher_4_kstat = kstat_create("zfs", 0, "fletcher_4_bench", "misc",
KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VIRTUAL);
@@ -795,8 +785,6 @@ fletcher_4_init(void)
fletcher_4_kstat_addr);
kstat_install(fletcher_4_kstat);
}
#else
fletcher_4_benchmark(NULL);
#endif
/* Finish initialization */
module/zcommon/zfs_prop.c
+14
View File
@@ -865,10 +865,23 @@ zfs_prop_align_right(zfs_prop_t prop)
#endif
#if defined(_KERNEL)
#include <sys/simd.h>
#if defined(HAVE_KERNEL_FPU_INTERNAL)
union fpregs_state **zfs_kfpu_fpregs;
EXPORT_SYMBOL(zfs_kfpu_fpregs);
#endif /* HAVE_KERNEL_FPU_INTERNAL */
static int __init
zcommon_init(void)
{
int error = kfpu_init();
if (error)
return (error);
fletcher_4_init();
return (0);
}
@@ -876,6 +889,7 @@ static void __exit
zcommon_fini(void)
{
fletcher_4_fini();
kfpu_fini();
}
module_init(zcommon_init);