}
release(release_set);
}
+
+/**
+ * Gives fragmentation a numeric value.
+ *
+ * Following algorithm applies value to each existing free unallocated block.
+ * Value of single block is a multiply of size and per-byte-value.
+ * Per-byte-value is greater for larger blocks.
+ * Assume block size X has value per-byte p; then block size 2*X will have per-byte value 1.1*p.
+ *
+ * This could be expressed in logarithms, but for speed this is interpolated inside ranges.
+ * [1] [2..3] [4..7] [8..15] ...
+ * ^ ^ ^ ^
+ * 1.1 1.1^2 1.1^3 1.1^4 ...
+ *
+ * Final score is obtained by proportion between score that would have been obtained
+ * in condition of absolute fragmentation and score in no fragmentation at all.
+ */
+double Allocator::get_fragmentation_score()
+{
+ // this value represents how much worth is 2X bytes in one chunk then in X + X bytes
+ static const double double_size_worth = 1.1 ;
+ std::vector<double> scales{1};
+ double score_sum = 0;
+ size_t sum = 0;
+
+ auto get_score = [&](size_t v) -> double {
+ size_t sc = sizeof(v) * 8 - clz(v) - 1; //assign to grade depending on log2(len)
+ while (scales.size() <= sc + 1) {
+ //unlikely expand scales vector
+ scales.push_back(scales[scales.size() - 1] * double_size_worth);
+ }
+
+ size_t sc_shifted = size_t(1) << sc;
+ double x = double(v - sc_shifted) / sc_shifted; //x is <0,1) in its scale grade
+ // linear extrapolation in its scale grade
+ double score = (sc_shifted ) * scales[sc] * (1-x) +
+ (sc_shifted * 2) * scales[sc+1] * x;
+ return score;
+ };
+
+ auto iterated_allocation = [&](size_t off, size_t len) {
+ ceph_assert(len > 0);
+ score_sum += get_score(len);
+ sum += len;
+ };
+ dump(iterated_allocation);
+
+
+ double ideal = get_score(sum);
+ double terrible = sum * get_score(1);
+ return (ideal - score_sum) / (ideal - terrible);
+}
#include <ostream>
#include "include/assert.h"
#include "os/bluestore/bluestore_types.h"
+#include <functional>
class FreelistManager;
void release(const PExtentVector& release_set);
virtual void dump() = 0;
+ virtual void dump(std::function<void(uint64_t offset, uint64_t length)> notify) = 0;
virtual void init_add_free(uint64_t offset, uint64_t length) = 0;
virtual void init_rm_free(uint64_t offset, uint64_t length) = 0;
{
return 0.0;
}
-
+ virtual double get_fragmentation_score();
virtual void shutdown() = 0;
static Allocator *create(CephContext* cct, string type, int64_t size,
int64_t block_size);
++it;
}
}
+
+void BitmapAllocator::dump(std::function<void(uint64_t offset, uint64_t length)> notify)
+{
+ size_t alloc_size = get_min_alloc_size();
+ auto multiply_by_alloc_size = [alloc_size, notify](size_t off, size_t len) {
+ notify(off * alloc_size, len * alloc_size);
+ };
+ std::lock_guard<std::mutex> lck(lock);
+ l1.dump(multiply_by_alloc_size);
+}
}
void dump() override;
+ void dump(std::function<void(uint64_t offset, uint64_t length)> notify) override;
double get_fragmentation(uint64_t) override
{
return _get_fragmentation();
}
}
+void StupidAllocator::dump(std::function<void(uint64_t offset, uint64_t length)> notify)
+{
+ std::lock_guard<std::mutex> l(lock);
+ for (unsigned bin = 0; bin < free.size(); ++bin) {
+ for (auto p = free[bin].begin(); p != free[bin].end(); ++p) {
+ notify(p.get_start(), p.get_len());
+ }
+ }
+}
+
void StupidAllocator::init_add_free(uint64_t offset, uint64_t length)
{
std::lock_guard<std::mutex> l(lock);
double get_fragmentation(uint64_t alloc_unit) override;
void dump() override;
+ void dump(std::function<void(uint64_t offset, uint64_t length)> notify) override;
void init_add_free(uint64_t offset, uint64_t length) override;
void init_rm_free(uint64_t offset, uint64_t length) override;
bins_overall[cbits(free_seq_cnt) - 1]++;
}
}
+
+inline ssize_t AllocatorLevel01Loose::count_0s(slot_t slot_val, size_t start_pos)
+ {
+ #ifdef __GNUC__
+ size_t pos = __builtin_ffsll(slot_val >> start_pos);
+ if (pos == 0)
+ return sizeof(slot_t)*8 - start_pos;
+ return pos - 1;
+ #else
+ size_t pos = start_pos;
+ slot_t mask = slot_t(1) << pos;
+ while (pos < bits_per_slot && (slot_val & mask) == 0) {
+ mask <<= 1;
+ pos++;
+ }
+ return pos - start_pos;
+ #endif
+ }
+
+ inline ssize_t AllocatorLevel01Loose::count_1s(slot_t slot_val, size_t start_pos)
+ {
+ return count_0s(~slot_val, start_pos);
+ }
+void AllocatorLevel01Loose::dump(
+ std::function<void(uint64_t offset, uint64_t length)> notify)
+{
+ size_t len = 0;
+ size_t off = 0;
+ for (size_t i = 0; i < l1.size(); i++)
+ {
+ for (size_t j = 0; j < L1_ENTRIES_PER_SLOT * L1_ENTRY_WIDTH; j += L1_ENTRY_WIDTH)
+ {
+ size_t w = (l1[i] >> j) & L1_ENTRY_MASK;
+ switch (w) {
+ case L1_ENTRY_FULL:
+ if (len > 0) {
+ notify(off, len);
+ len = 0;
+ }
+ break;
+ case L1_ENTRY_FREE:
+ if (len == 0)
+ off = ( ( bits_per_slot * i + j ) / L1_ENTRY_WIDTH ) * slots_per_slotset * bits_per_slot;
+ len += bits_per_slotset;
+ break;
+ case L1_ENTRY_PARTIAL:
+ size_t pos = ( ( bits_per_slot * i + j ) / L1_ENTRY_WIDTH ) * slots_per_slotset;
+ for (size_t t = 0; t < slots_per_slotset; t++) {
+ size_t p = 0;
+ slot_t allocation_pattern = l0[pos + t];
+ while (p < bits_per_slot) {
+ if (len == 0) {
+ //continue to skip allocated space, meaning bits set to 0
+ ssize_t alloc_count = count_0s(allocation_pattern, p);
+ p += alloc_count;
+ //now we are switched to expecting free space
+ if (p < bits_per_slot) {
+ //now @p are 1s
+ ssize_t free_count = count_1s(allocation_pattern, p);
+ assert(free_count > 0);
+ len = free_count;
+ off = (pos + t) * bits_per_slot + p;
+ p += free_count;
+ }
+ } else {
+ //continue free region
+ ssize_t free_count = count_1s(allocation_pattern, p);
+ if (free_count == 0) {
+ notify(off, len);
+ len = 0;
+ } else {
+ p += free_count;
+ len += free_count;
+ }
+ }
+ }
+ }
+ break;
+ }
+ }
+ }
+ if (len > 0)
+ notify(off, len);
+}
+
// fitting into cache line on x86_64
static const size_t slotset_width = 8; // 8 slots per set
+static const size_t slots_per_slotset = 8;
static const size_t slotset_bytes = sizeof(slot_t) * slotset_width;
static const size_t bits_per_slot = sizeof(slot_t) * 8;
static const size_t bits_per_slotset = slotset_bytes * 8;
L1_ENTRY_NOT_USED = 0x02,
L1_ENTRY_FREE = 0x03,
CHILD_PER_SLOT = bits_per_slot / L1_ENTRY_WIDTH, // 32
+ L1_ENTRIES_PER_SLOT = bits_per_slot / L1_ENTRY_WIDTH, //32
CHILD_PER_SLOT_L0 = bits_per_slot, // 64
};
uint64_t _children_per_slot() const override
}
void collect_stats(
std::map<size_t, size_t>& bins_overall) override;
+
+ static inline ssize_t count_0s(slot_t slot_val, size_t start_pos);
+ static inline ssize_t count_1s(slot_t slot_val, size_t start_pos);
+ void dump(std::function<void(uint64_t offset, uint64_t length)> notify);
};
+
class AllocatorLevel01Compact : public AllocatorLevel01
{
uint64_t _children_per_slot() const override
projects / ceph.git / commitdiff