Displaying 11 results from an estimated 11 matches for "lfsr_taps".
2015 Apr 13
1
[PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock
...v_lock_hash = alloc_large_system_hash("PV qspinlock",
> >>+ sizeof(struct pv_hash_bucket),
> >>+ pv_hash_size, 0, HASH_EARLY,
> >>+ &pv_lock_hash_bits, NULL,
> >>+ pv_hash_size, pv_hash_size);
> > pv_taps = lfsr_taps(pv_lock_hash_bits);
> >
>
> I don't understand what you meant here.
Let me explain (even though I propose taking all the LFSR stuff out).
pv_lock_hash_bit is a runtime variable, therefore it cannot compile time
evaluate the forest of if statements required to compute the taps val...
2015 Apr 13
1
[PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock
...v_lock_hash = alloc_large_system_hash("PV qspinlock",
> >>+ sizeof(struct pv_hash_bucket),
> >>+ pv_hash_size, 0, HASH_EARLY,
> >>+ &pv_lock_hash_bits, NULL,
> >>+ pv_hash_size, pv_hash_size);
> > pv_taps = lfsr_taps(pv_lock_hash_bits);
> >
>
> I don't understand what you meant here.
Let me explain (even though I propose taking all the LFSR stuff out).
pv_lock_hash_bit is a runtime variable, therefore it cannot compile time
evaluate the forest of if statements required to compute the taps val...
2015 Mar 19
4
[PATCH 8/9] qspinlock: Generic paravirt support
...b/include/linux/lfsr.h
@@ -0,0 +1,49 @@
+#ifndef _LINUX_LFSR_H
+#define _LINUX_LFSR_H
+
+/*
+ * Simple Binary Galois Linear Feedback Shift Register
+ *
+ * http://en.wikipedia.org/wiki/Linear_feedback_shift_register
+ *
+ */
+
+extern void __lfsr_needs_more_taps(void);
+
+static __always_inline u32 lfsr_taps(int bits)
+{
+ if (bits == 1) return 0x0001;
+ if (bits == 2) return 0x0001;
+ if (bits == 3) return 0x0003;
+ if (bits == 4) return 0x0009;
+ if (bits == 5) return 0x0012;
+ if (bits == 6) return 0x0021;
+ if (bits == 7) return 0x0041;
+ if (bits == 8) return 0x008E;
+ if (bits == 9) retu...
2015 Mar 19
4
[PATCH 8/9] qspinlock: Generic paravirt support
...b/include/linux/lfsr.h
@@ -0,0 +1,49 @@
+#ifndef _LINUX_LFSR_H
+#define _LINUX_LFSR_H
+
+/*
+ * Simple Binary Galois Linear Feedback Shift Register
+ *
+ * http://en.wikipedia.org/wiki/Linear_feedback_shift_register
+ *
+ */
+
+extern void __lfsr_needs_more_taps(void);
+
+static __always_inline u32 lfsr_taps(int bits)
+{
+ if (bits == 1) return 0x0001;
+ if (bits == 2) return 0x0001;
+ if (bits == 3) return 0x0003;
+ if (bits == 4) return 0x0009;
+ if (bits == 5) return 0x0012;
+ if (bits == 6) return 0x0021;
+ if (bits == 7) return 0x0041;
+ if (bits == 8) return 0x008E;
+ if (bits == 9) retu...
2015 Apr 09
6
[PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock
...line aligned.
> + */
> + pv_lock_hash = alloc_large_system_hash("PV qspinlock",
> + sizeof(struct pv_hash_bucket),
> + pv_hash_size, 0, HASH_EARLY,
> + &pv_lock_hash_bits, NULL,
> + pv_hash_size, pv_hash_size);
pv_taps = lfsr_taps(pv_lock_hash_bits);
> +}
> +
> +static inline u32 hash_align(u32 hash)
> +{
> + return hash & ~(PV_HB_PER_LINE - 1);
> +}
> +
> +static struct qspinlock **pv_hash(struct qspinlock *lock, struct pv_node *node)
> +{
> + unsigned long init_hash, hash = hash_ptr(lock,...
2015 Apr 09
6
[PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock
...line aligned.
> + */
> + pv_lock_hash = alloc_large_system_hash("PV qspinlock",
> + sizeof(struct pv_hash_bucket),
> + pv_hash_size, 0, HASH_EARLY,
> + &pv_lock_hash_bits, NULL,
> + pv_hash_size, pv_hash_size);
pv_taps = lfsr_taps(pv_lock_hash_bits);
> +}
> +
> +static inline u32 hash_align(u32 hash)
> +{
> + return hash & ~(PV_HB_PER_LINE - 1);
> +}
> +
> +static struct qspinlock **pv_hash(struct qspinlock *lock, struct pv_node *node)
> +{
> + unsigned long init_hash, hash = hash_ptr(lock,...
2015 Mar 18
2
[PATCH 8/9] qspinlock: Generic paravirt support
On 03/16/2015 09:16 AM, Peter Zijlstra wrote:
> Implement simple paravirt support for the qspinlock.
>
> Provide a separate (second) version of the spin_lock_slowpath for
> paravirt along with a special unlock path.
>
> The second slowpath is generated by adding a few pv hooks to the
> normal slowpath, but where those will compile away for the native
> case, they expand
2015 Mar 18
2
[PATCH 8/9] qspinlock: Generic paravirt support
On 03/16/2015 09:16 AM, Peter Zijlstra wrote:
> Implement simple paravirt support for the qspinlock.
>
> Provide a separate (second) version of the spin_lock_slowpath for
> paravirt along with a special unlock path.
>
> The second slowpath is generated by adding a few pv hooks to the
> normal slowpath, but where those will compile away for the native
> case, they expand
2015 Apr 09
0
[PATCH v15 09/15] pvqspinlock: Implement simple paravirt support for the qspinlock
...; + */
>> + pv_lock_hash = alloc_large_system_hash("PV qspinlock",
>> + sizeof(struct pv_hash_bucket),
>> + pv_hash_size, 0, HASH_EARLY,
>> + &pv_lock_hash_bits, NULL,
>> + pv_hash_size, pv_hash_size);
> pv_taps = lfsr_taps(pv_lock_hash_bits);
>
I don't understand what you meant here.
>> +}
>> +
>> +static inline u32 hash_align(u32 hash)
>> +{
>> + return hash& ~(PV_HB_PER_LINE - 1);
>> +}
>> +
>> +static struct qspinlock **pv_hash(struct qspinlock *lock, s...
2015 Apr 07
18
[PATCH v15 00/15] qspinlock: a 4-byte queue spinlock with PV support
v14->v15:
- Incorporate PeterZ's v15 qspinlock patch and improve upon the PV
qspinlock code by dynamically allocating the hash table as well
as some other performance optimization.
- Simplified the Xen PV qspinlock code as suggested by David Vrabel
<david.vrabel at citrix.com>.
- Add benchmarking data for 3.19 kernel to compare the performance
of a spinlock heavy test
2015 Apr 07
18
[PATCH v15 00/15] qspinlock: a 4-byte queue spinlock with PV support
v14->v15:
- Incorporate PeterZ's v15 qspinlock patch and improve upon the PV
qspinlock code by dynamically allocating the hash table as well
as some other performance optimization.
- Simplified the Xen PV qspinlock code as suggested by David Vrabel
<david.vrabel at citrix.com>.
- Add benchmarking data for 3.19 kernel to compare the performance
of a spinlock heavy test