Parameter auto-tuning for the marginal-hits strategy

[hazelnut-99]

Summary

Added a new slabrebalance strategy: MarginalHitsStrategyNew, which builds upon the existing MarginalHitsStrategy. The goal is to mitigate slab thrashing issues by adding tuning mechanisms.

---

Different Strategy Configurations for Testing

The following configurations are supported and can be tested for performance comparison:

Option 1: Hits-Per-Slab

#include "cachelib/allocator/HitsPerSlabStrategy.h"

auto rbConfig = HitsPerSlabStrategy::Config{};
config.enablePoolRebalancing(
  std::make_shared<HitsPerSlabStrategy>(rbConfig),
  std::chrono::seconds(1));

---

Option 2: Marginal-Hits (Original) + Warm Tail + Cold Tail

#include "cachelib/allocator/MarginalHitsStrategy.h"

config.enableTailHitsTracking(); 
config.countColdTailHitsOnly = false;
auto rbConfig = MarginalHitsStrategy::Config{};
config.enablePoolRebalancing(
  std::make_shared<MarginalHitsStrategy>(rbConfig),
  std::chrono::seconds(1));

---

Option 3: Marginal-Hits (Original) + Cold Tail Only

#include "cachelib/allocator/MarginalHitsStrategy.h"

config.enableTailHitsTracking(); 
config.countColdTailHitsOnly = true;
auto rbConfig = MarginalHitsStrategy::Config{};
config.enablePoolRebalancing(
  std::make_shared<MarginalHitsStrategy>(rbConfig),
  std::chrono::seconds(1));

---

Option 4: Marginal-Hits-New (Tuned) + Warm Tail + Cold Tail

#include "cachelib/allocator/MarginalHitsStrategyNew.h"

config.enableTailHitsTracking(); 
config.countColdTailHitsOnly = false;
auto rbConfig = MarginalHitsStrategyNew::Config{};
config.enablePoolRebalancing(
  std::make_shared<MarginalHitsStrategyNew>(rbConfig),
  std::chrono::seconds(1));

---

Option 5: Marginal-Hits-New (Tuned) + Cold Tail Only

#include "cachelib/allocator/MarginalHitsStrategyNew.h"

config.enableTailHitsTracking(); 
config.countColdTailHitsOnly = true;
auto rbConfig = MarginalHitsStrategyNew::Config{};
config.enablePoolRebalancing(
  std::make_shared<MarginalHitsStrategyNew>(rbConfig),
  std::chrono::seconds(1));

---

Option 6: LRU-Tail-Age

#include "cachelib/allocator/LruTailAgeStrategy.h"

auto rbConfig = LruTailAgeStrategy::Config{};
config.enablePoolRebalancing(
  std::make_shared<LruTailAgeStrategy>(rbConfig),
  std::chrono::seconds(1));

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