Staging
v0.6.0
v0.6.0
Revision a0783cd0c810504427777e8aae20d5f4f8b652a0 authored by Corinna Vinschen on 19 November 2019, 09:09:39 UTC, committed by David S. Miller on 20 November 2019, 00:41:11 UTC
During performance testing, I found that one of my r8169 NICs suffered a major performance loss, a 8168c model. Running netperf's TCP_STREAM test didn't return the expected throughput of > 900 Mb/s, but rather only about 22 Mb/s. Strange enough, running the TCP_MAERTS and UDP_STREAM tests all returned with throughput > 900 Mb/s, as did TCP_STREAM with the other r8169 NICs I can test (either one of 8169s, 8168e, 8168f). Bisecting turned up commit 93681cd7d94f83903cb3f0f95433d10c28a7e9a5, "r8169: enable HW csum and TSO" as the culprit. I added my 8168c version, RTL_GIGA_MAC_VER_22, to the code special-casing the 8168evl as per the patch below. This fixed the performance problem for me. Fixes: 93681cd7d94f ("r8169: enable HW csum and TSO") Signed-off-by: Corinna Vinschen <vinschen@redhat.com> Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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syscall.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/export.h>
#include <asm/syscall.h>
static int collect_syscall(struct task_struct *target, struct syscall_info *info)
{
struct pt_regs *regs;
if (!try_get_task_stack(target)) {
/* Task has no stack, so the task isn't in a syscall. */
memset(info, 0, sizeof(*info));
info->data.nr = -1;
return 0;
}
regs = task_pt_regs(target);
if (unlikely(!regs)) {
put_task_stack(target);
return -EAGAIN;
}
info->sp = user_stack_pointer(regs);
info->data.instruction_pointer = instruction_pointer(regs);
info->data.nr = syscall_get_nr(target, regs);
if (info->data.nr != -1L)
syscall_get_arguments(target, regs,
(unsigned long *)&info->data.args[0]);
put_task_stack(target);
return 0;
}
/**
* task_current_syscall - Discover what a blocked task is doing.
* @target: thread to examine
* @info: structure with the following fields:
* .sp - filled with user stack pointer
* .data.nr - filled with system call number or -1
* .data.args - filled with @maxargs system call arguments
* .data.instruction_pointer - filled with user PC
*
* If @target is blocked in a system call, returns zero with @info.data.nr
* set to the the call's number and @info.data.args filled in with its
* arguments. Registers not used for system call arguments may not be available
* and it is not kosher to use &struct user_regset calls while the system
* call is still in progress. Note we may get this result if @target
* has finished its system call but not yet returned to user mode, such
* as when it's stopped for signal handling or syscall exit tracing.
*
* If @target is blocked in the kernel during a fault or exception,
* returns zero with *@info.data.nr set to -1 and does not fill in
* @info.data.args. If so, it's now safe to examine @target using
* &struct user_regset get() calls as long as we're sure @target won't return
* to user mode.
*
* Returns -%EAGAIN if @target does not remain blocked.
*/
int task_current_syscall(struct task_struct *target, struct syscall_info *info)
{
long state;
unsigned long ncsw;
if (target == current)
return collect_syscall(target, info);
state = target->state;
if (unlikely(!state))
return -EAGAIN;
ncsw = wait_task_inactive(target, state);
if (unlikely(!ncsw) ||
unlikely(collect_syscall(target, info)) ||
unlikely(wait_task_inactive(target, state) != ncsw))
return -EAGAIN;
return 0;
}
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