diff --git a/cache_slice/Cargo.toml b/cache_slice/Cargo.toml
index eeafc02..5d8b255 100644
--- a/cache_slice/Cargo.toml
+++ b/cache_slice/Cargo.toml
@@ -4,3 +4,5 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+raw-cpuid = "11.0.2"
+nix = "0.29.0"
diff --git a/cache_slice/src/arch.rs b/cache_slice/src/arch.rs
new file mode 100644
index 0000000..1793265
--- /dev/null
+++ b/cache_slice/src/arch.rs
@@ -0,0 +1,241 @@
+use raw_cpuid::CpuId;
+use crate::arch::CpuClass::{IntelCore, IntelXeon, IntelXeonSP};
+
+pub(crate) enum CpuClass {
+    IntelCore,
+    IntelXeon,
+    IntelXeonSP,
+    // Add further CPUs later on
+}
+
+pub(crate) fn determine_cpu_class() -> Option<CpuClass> {
+    let cpuid = CpuId::new();
+    let info = if let Some(info) = cpuid.get_feature_info() {
+        info
+    } else {
+        return None;
+    };
+
+    // Todo, sift through the documentation to add support for more CPUs
+    match (info.family_id(), info.model_id()) {
+        (0x06, 0x4f)
+        | (0x06, 0x2d)
+        | (0x06, 0x3e)
+        | (06, 0x3f)
+        | (0x06, 0x56) => {
+            Some(IntelXeon)
+        }
+        (0x06, 0x55) => {
+            Some(IntelXeonSP)
+        }
+        // 42, 58, 60, 69, 70, 61, 71, 78, 94, 142, 158
+        (0x06, 0x2a)
+        | (0x06, 0x3a)
+        | (0x06, 0x3c)
+        | (0x06, 0x45)
+        | (0x06, 0x46)
+        | (0x06, 0x3d)
+        | (0x06, 0x47)
+        | (0x06, 0x4e)
+        | (0x06, 0x5e)
+        | (0x06, 0x8e)
+        | (0x06, 0x9e) => {
+            Some(IntelCore)
+        }
+        _ => {
+            None
+        }
+    }
+}
+
+pub(crate) fn get_performance_counters_xeon() -> Option<&'static XeonPerfCounters> {
+    let cpuid = CpuId::new();
+    let info = if let Some(info) = cpuid.get_feature_info() {
+        info
+    } else {
+        return None;
+    };
+    if info.family_id() != 6 {
+        return None;
+    }
+    match info.model_id() {
+        0x2d /* 45 */ => Some(&SANDY_BRIDGE_XEON),
+        0x3e /* 62 */ => Some(&IVY_BRIDGE_XEON),
+        0x3f /* 63 */ => Some(&HASWELL_XEON),
+        0x56 /* 86 */ => Some(&BROADWELL_XEON),
+        _ => None,
+    }
+}
+
+pub(crate) fn get_performance_counters_core() -> Option<&'static CorePerfCounters> {
+    let cpuid = CpuId::new();
+    let info = if let Some(info) = cpuid.get_feature_info() {
+        info
+    } else {
+        return None;
+    };
+    if info.family_id() != 6 {
+        return None;
+    }
+    // TODO, review if the list can be extended to further CPUs
+    // TODO, add post Cannon Lake stuff
+    match info.model_id() {
+        0x2a
+        | 0x3a
+        | 0x3c
+        | 0x45
+        | 0x46
+        | 0x3d
+        | 0x47 => Some(&SANDYBRIDGE_TO_BROADWELL_CORE),
+        0x4e
+        | 0x5e
+        | 0x8e
+        | 0x9e => Some(&SKYLAKE_KABYLAKE_CORE),
+        _ => None,
+    }
+}
+
+pub struct XeonPerfCounters {
+    pub max_slice: u16,
+    pub msr_pmon_ctr0: &'static [u64],
+    pub msr_pmon_box_filter: &'static [u64],
+    pub msr_pmon_ctl0: &'static [u64],
+    pub msr_pmon_box_ctl: &'static [u64],
+    pub val_box_freeze: u64,
+    pub val_box_reset: u64,
+    pub val_enable_counting: u64,
+    pub val_select_event: u64,
+    pub val_filter: u64,
+    pub val_box_unfreeze: u64,
+}
+
+pub struct CorePerfCounters {
+    pub max_slice: u16,
+    pub msr_unc_perf_global_ctr: u64,
+    pub val_enable_ctrs: u64,
+    pub msr_unc_cbo_perfevtsel0: &'static [u64],
+    pub msr_unc_cbo_per_ctr0: &'static [u64],
+    pub val_disable_ctrs: u64,
+    pub val_select_evt_core: u64,
+    pub val_reset_ctrs: u64,
+}
+
+const SANDY_BRIDGE_XEON: XeonPerfCounters = XeonPerfCounters {
+    max_slice: 8,
+    msr_pmon_ctr0: &[0xd16, 0xd36, 0xd56, 0xd76,
+        0xd96, 0xdb6, 0xdd6, 0xdf6],
+    msr_pmon_box_filter: &[0xd14, 0xd34, 0xd54, 0xd74, 0xd94, 0xdb4, 0xdd4, 0xdf4],
+    msr_pmon_ctl0: &[0xd10, 0xd30, 0xd50, 0xd70,
+        0xd90, 0xdb0, 0xdd0, 0xdf0],
+    msr_pmon_box_ctl: &[0xd04, 0xd24, 0xd44, 0xd64, 0xd84, 0xda4, 0xdc4, 0xde4],
+    val_box_freeze: 0x10100,
+    val_box_reset: 0x10103,
+    val_enable_counting: 0x400000,
+    val_select_event: 0x401134,
+    val_filter: 0x7c0000,
+    val_box_unfreeze: 0x10000,
+};
+
+const IVY_BRIDGE_XEON: XeonPerfCounters = XeonPerfCounters {
+    max_slice: 15,
+    msr_pmon_ctr0: &[0xd16, 0xd36, 0xd56, 0xd76, 0xd96, 0xdb6, 0xdd6, 0xdf6,
+        0xe16, 0xe36, 0xe56, 0xe76, 0xe96, 0xeb6, 0xed6],
+    msr_pmon_box_filter: &[0xd14, 0xd34, 0xd54, 0xd74, 0xd94, 0xdb4, 0xdd4, 0xdf4,
+        0xe14, 0xe34, 0xe54, 0xe74, 0xe94, 0xeb4, 0xed4],
+    msr_pmon_ctl0: &[0xd10, 0xd30, 0xd50, 0xd70, 0xd90, 0xdb0, 0xdd0, 0xdf0,
+        0xe10, 0xe30, 0xe50, 0xe70, 0xe90, 0xeb0, 0xed0],
+    msr_pmon_box_ctl: &[0xd04, 0xd24, 0xd44, 0xd64, 0xd84, 0xda4, 0xdc4, 0xde4,
+        0xe04, 0xe24, 0xe44, 0xe64, 0xe84, 0xea4, 0xec4],
+    val_box_freeze: 0x30100,
+    val_box_reset: 0x30103,
+    val_enable_counting: 0x400000,
+    val_select_event: 0x401134,
+    val_filter: 0x7e0010,
+    val_box_unfreeze: 0x30000,
+};
+
+const HASWELL_XEON: XeonPerfCounters = XeonPerfCounters {
+    max_slice: 18,
+    msr_pmon_ctr0: &[0xe08, 0xe18, 0xe28, 0xe38, 0xe48, 0xe58, 0xe68, 0xe78, 0xe88,
+        0xe98, 0xea8, 0xeb8, 0xec8, 0xed8, 0xee8, 0xef8, 0xf08, 0xf18],
+    msr_pmon_box_filter: &[0xe05, 0xe15, 0xe25, 0xe35, 0xe45, 0xe55, 0xe65, 0xe75, 0xe85,
+        0xe95, 0xea5, 0xeb5, 0xec5, 0xed5, 0xee5, 0xef5, 0xf05, 0xf15],
+    msr_pmon_ctl0: &[0xe01, 0xe11, 0xe21, 0xe31, 0xe41, 0xe51, 0xe61, 0xe71, 0xe81,
+        0xe91, 0xea1, 0xeb1, 0xec1, 0xed1, 0xee1, 0xef1, 0xf01, 0xf11],
+    msr_pmon_box_ctl: &[0xe00, 0xe10, 0xe20, 0xe30, 0xe40, 0xe50, 0xe60, 0xe70, 0xe80,
+        0xe90, 0xea0, 0xeb0, 0xec0, 0xed0, 0xee0, 0xef0, 0xf00, 0xf10],
+    val_box_freeze: 0x30100,
+    val_box_reset: 0x30103,
+    val_enable_counting: 0x400000,
+    val_select_event: 0x401134,
+    val_filter: 0x7e0020,
+    val_box_unfreeze: 0x30000,
+};
+
+const BROADWELL_XEON: XeonPerfCounters = XeonPerfCounters {
+    max_slice: 24,
+    msr_pmon_ctr0: &[0xe08, 0xe18, 0xe28, 0xe38, 0xe48, 0xe58, 0xe68, 0xe78,
+        0xe88, 0xe98, 0xea8, 0xeb8, 0xec8, 0xed8, 0xee8, 0xef8,
+        0xf08, 0xf18, 0xf28, 0xf38, 0xf48, 0xf58, 0xf68, 0xf78],
+    msr_pmon_box_filter: &[0xe05, 0xe15, 0xe25, 0xe35, 0xe45, 0xe55, 0xe65, 0xe75,
+        0xe85, 0xe95, 0xea5, 0xeb5, 0xec5, 0xed5, 0xee5, 0xef5,
+        0xf05, 0xf15, 0xf25, 0xf35, 0xf45, 0xf55, 0xf65, 0xf75],
+    msr_pmon_ctl0: &[0xe01, 0xe11, 0xe21, 0xe31, 0xe41, 0xe51, 0xe61, 0xe71,
+        0xe81, 0xe91, 0xea1, 0xeb1, 0xec1, 0xed1, 0xee1, 0xef1,
+        0xf01, 0xf11, 0xf21, 0xf31, 0xf41, 0xf51, 0xf61, 0xf71],
+    msr_pmon_box_ctl: &[0xe00, 0xe10, 0xe20, 0xe30, 0xe40, 0xe50, 0xe60, 0xe70,
+        0xe80, 0xe90, 0xea0, 0xeb0, 0xec0, 0xed0, 0xee0, 0xef0,
+        0xf00, 0xf10, 0xf20, 0xf30, 0xf40, 0xf50, 0xf60, 0xf70],
+    val_box_freeze: 0x30100,
+    val_box_reset: 0x30103,
+    val_enable_counting: 0x400000,
+    val_select_event: 0x401134,
+    val_filter: 0xfe0020,
+    val_box_unfreeze: 0x30000,
+};
+
+// TODO find appropriate values
+const ALDER_LAKE_TO_RAPTOR_LAKE_CORE: CorePerfCounters = CorePerfCounters {
+    max_slice: 10,
+    msr_unc_perf_global_ctr: 0x2ff0,
+    val_enable_ctrs: 0, // TODO
+    msr_unc_cbo_perfevtsel0: &[0x2000, 0x2008, 0x2010, 0x2018, 0x2020, 0x2028, 0x2030, 0x2038, 0x2040, 0x2048],
+    msr_unc_cbo_per_ctr0: &[0x2002, 0x200a, 0x2012, 0x201a, 0x2022, 0x202a, 0x2032, 0x203a, 0x2042, 0x204a],
+    val_disable_ctrs: 0, // TODO
+    val_select_evt_core: 0, // TODO
+    val_reset_ctrs: 0, // TODO
+};
+
+// TODO verify his on ICELAKE, and appropriate values. Also deal with backport Cypress Cove ?
+const CANNON_LAKE_TO_TIGER_LAKE_CORE: CorePerfCounters = CorePerfCounters {
+    max_slice: 8, // TODO
+    msr_unc_perf_global_ctr: 0xe01,
+    val_enable_ctrs: 0, // TODO
+    msr_unc_cbo_perfevtsel0: &[0x700, 0x708, 0x710, 0x718, 0x720, 0x728, 0x730, 0x738],
+    msr_unc_cbo_per_ctr0: &[0x702, 0x70a, 0x712, 0x71a, 0x722, 0x72a, 0x732, 0x73a],
+    val_disable_ctrs: 0x0, // TODO
+    val_select_evt_core: 0, // TODO
+    val_reset_ctrs: 0x0, // TODO
+};
+
+const SKYLAKE_KABYLAKE_CORE: CorePerfCounters = CorePerfCounters {
+    max_slice: 7,
+    msr_unc_perf_global_ctr: 0xe01,
+    val_enable_ctrs: 0x20000000,
+    msr_unc_cbo_perfevtsel0: &[0x700, 0x710, 0x720, 0x730, 0x740, 0x750, 0x760],
+    msr_unc_cbo_per_ctr0: &[0x706, 0x716, 0x726, 0x736, 0x746, 0x756, 0x766],
+    val_disable_ctrs: 0x0,
+    val_select_evt_core: 0x408f34,
+    val_reset_ctrs: 0x0,
+};
+
+const SANDYBRIDGE_TO_BROADWELL_CORE: CorePerfCounters = CorePerfCounters {
+    max_slice: 0,
+    msr_unc_perf_global_ctr: 0x391,
+    val_enable_ctrs: 0x2000000f,
+    msr_unc_cbo_perfevtsel0: &[0x700, 0x710, 0x720, 0x730],
+    msr_unc_cbo_per_ctr0: &[0x706, 0x716, 0x726, 0x736],
+    val_disable_ctrs: 0x0,
+    val_select_evt_core: 0x408f34,
+    val_reset_ctrs: 0x0,
+};
diff --git a/cache_slice/src/bin/scan.rs b/cache_slice/src/bin/scan.rs
new file mode 100644
index 0000000..a862996
--- /dev/null
+++ b/cache_slice/src/bin/scan.rs
@@ -0,0 +1,37 @@
+use cache_slice::monitor_address;
+use cache_slice::utils::core_per_package;
+use nix::sched::{sched_getaffinity, CpuSet};
+
+
+pub fn main() {
+    let nb_cores = core_per_package();
+    println!("Found {} cores", nb_cores);
+
+    let target = vec![0x0123456789abcdefu64, 64];
+    for core in 0..CpuSet::count() {
+        for addr in target.iter() {
+            let res = unsafe { monitor_address(addr as *const u64 as *const u8, core as u8, nb_cores) };
+            let slice = res.iter().enumerate().max_by_key(|(i, val)| { val });
+            match slice {
+                Some((slice, _)) => {
+                    println!("({:2}) Slice for addr {:x}: {}", core, addr as *const u64 as usize, slice)
+                }
+                None => {
+                    eprintln!("({:2}) Failed to find slice for addr {:x}", core, addr as *const u64 as usize)
+                }
+            }
+        }
+        for addr in target.iter() {
+            let res = unsafe { monitor_address(addr as *const u64 as *const u8, 0, nb_cores) };
+            let slice = res.iter().enumerate().max_by_key(|(i, val)| { val });
+            match slice {
+                Some((slice, _)) => {
+                    println!("({:2}) Slice for addr {:x}: {}", 0, addr as *const u64 as usize, slice)
+                }
+                None => {
+                    eprintln!("({:2}) Failed to find slice for addr {:x}", 0, addr as *const u64 as usize)
+                }
+            }
+        }
+    }
+}
diff --git a/cache_slice/src/lib.rs b/cache_slice/src/lib.rs
index 89e7ac1..9883c32 100644
--- a/cache_slice/src/lib.rs
+++ b/cache_slice/src/lib.rs
@@ -1,7 +1,109 @@
-pub mod msr;
+#![deny(unsafe_op_in_unsafe_fn)]
 
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
+use std::arch::x86_64::_mm_clflush;
+use crate::arch::CpuClass::{IntelCore, IntelXeon, IntelXeonSP};
+use crate::arch::get_performance_counters_xeon;
+use crate::Error::UnsupportedCPU;
+use crate::msr::{read_msr_on_cpu, write_msr_on_cpu};
+
+pub mod msr;
+pub mod utils;
+mod arch;
+
+pub enum Error {
+    UnsupportedCPU,
+    InvalidParameter,
+    IO(std::io::Error),
+}
+
+impl From<std::io::Error> for Error {
+    fn from(value: std::io::Error) -> Self {
+        Error::IO(value)
+    }
+}
+
+const NUM_POKE: usize = 10000;
+
+unsafe fn poke(addr: *const u8) {
+    for _i in 0..NUM_POKE {
+        unsafe { _mm_clflush(addr) };
+    }
+}
+
+unsafe fn monitor_xeon(addr: *const u8, cpu: u8, max_cbox: usize) -> Result<Vec<u32>, Error> {
+    let performance_counters = if let Some(p) = get_performance_counters_xeon() {
+        p
+    } else {
+        return Err(UnsupportedCPU);
+    };
+
+    if (performance_counters.max_slice as usize) < max_cbox {
+        return Err(Error::InvalidParameter);
+    }
+
+    // Freeze counters
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_ctr0[i], cpu, performance_counters.val_box_freeze)?;
+    }
+
+    // Reset counters
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_ctl0[i], cpu, performance_counters.val_box_reset)?;
+    }
+
+    // Enable counting
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_ctl0[i], cpu, performance_counters.val_enable_counting)?;
+    }
+
+    // Select event
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_ctl0[i], cpu, performance_counters.val_select_event)?;
+        write_msr_on_cpu(performance_counters.msr_pmon_box_filter[i], cpu, performance_counters.val_filter)?;
+    }
+
+    // Unfreeze
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_box_ctl[i], cpu, performance_counters.val_box_unfreeze)?;
+    }
+
+    unsafe { poke(addr) };
+
+    // Freeze counters
+    for i in 0..max_cbox {
+        write_msr_on_cpu(performance_counters.msr_pmon_ctr0[i], cpu, performance_counters.val_box_freeze)?;
+    }
+
+    // Read counters
+    let mut result = Vec::new();
+    for i in 0..max_cbox {
+        let result = read_msr_on_cpu(performance_counters.msr_pmon_ctr0[i], cpu)?;
+        result.push(result)
+    }
+
+    Ok(result)
+}
+
+fn monitor_core(addr: *const u8, cpu: u8, max_core: u8) -> Result<Vec<u32>, Error> {
+    // Note, we need to add the workaround for one missing perf counter here.
+    unimplemented!()
+}
+
+pub unsafe fn monitor_address(addr: *const u8, cpu: u8, max_cbox: u16) -> Result<Vec<u32>, Error> {
+    match arch::determine_cpu_class() {
+        Some(IntelCore) => {
+            unimplemented!()
+        }
+        Some(IntelXeon) => {
+            unsafe { monitor_xeon(addr, cpu, max_cbox as usize) }
+        }
+        Some(IntelXeonSP) => { // TODO
+            Err(UnsupportedCPU)
+        }
+        None => {
+            Err(UnsupportedCPU)
+        }
+    }
 }
 
 #[cfg(test)]
@@ -10,7 +112,7 @@ mod tests {
 
     #[test]
     fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+        let result = 2;
+        assert_eq!(result, 2);
     }
 }
diff --git a/cache_slice/src/msr.rs b/cache_slice/src/msr.rs
index 9b6ee29..27d128a 100644
--- a/cache_slice/src/msr.rs
+++ b/cache_slice/src/msr.rs
@@ -2,35 +2,35 @@ use core::mem::size_of;
 use std::format;
 use std::fs::{File, OpenOptions};
 use std::os::unix::fs::FileExt;
-use std::io::{Result, Error, ErrorKind};
+use std::io::{Result, Error};
 
-pub fn write_msr_on_cpu(msr: u32, cpu: u8, value: u64) -> Result<()> {
+pub fn write_msr_on_cpu(msr: u64, cpu: u8, value: u64) -> Result<()> {
     let path = format!("/dev/cpu/{}/msr", cpu);
-    let file : File = OpenOptions::new().write(true).open(path).expect("Failed to open MSR, are you running as root ?");
-    match file.write_at(&value.to_ne_bytes(), msr as u64) {
+    let file: File = OpenOptions::new().write(true).open(path).expect("Failed to open MSR, are you running as root ?");
+    match file.write_at(&value.to_ne_bytes(), msr) {
         Ok(size) => {
             if size == size_of::<u64>() {
                 Ok(())
             } else {
                 Err(Error::other("Failed to write complete value"))
             }
-        },
+        }
         Err(e) => Err(e)
     }
 }
 
-pub fn read_msr_on_cpu(msr: u32, cpu: u8) -> Result<u64> {
+pub fn read_msr_on_cpu(msr: u64, cpu: u8) -> Result<u64> {
     let path = format!("/dev/cpu/{}/msr", cpu);
-    let file : File = OpenOptions::new().read(true).open(path).expect("Failed to open MSR, are you running as root ?");
+    let file: File = OpenOptions::new().read(true).open(path).expect("Failed to open MSR, are you running as root ?");
     let mut read_data = [0u8; size_of::<u64>()];
-    match file.read_at(&mut read_data, msr as u64) {
+    match file.read_at(&mut read_data, msr) {
         Ok(size) => {
             if size == size_of::<u64>() {
                 Ok(u64::from_ne_bytes(read_data))
             } else {
                 Err(Error::other("Failed to write complete value"))
             }
-        },
+        }
         Err(e) => Err(e)
     }
 }
diff --git a/cache_slice/src/utils.rs b/cache_slice/src/utils.rs
new file mode 100644
index 0000000..681d815
--- /dev/null
+++ b/cache_slice/src/utils.rs
@@ -0,0 +1,55 @@
+use raw_cpuid::{CpuId, CpuIdReaderNative, ExtendedTopologyIter, TopologyType};
+
+fn get_topology_iterator() -> ExtendedTopologyIter<CpuIdReaderNative> {
+    let cpuid = CpuId::new();
+    let topology_iter = if let Some(t) = cpuid.get_extended_topology_info_v2() {
+        t
+    } else if let Some(t) = cpuid.get_extended_topology_info() {
+        t
+    } else {
+        panic!("Unsupported CPU");
+    };
+    topology_iter
+}
+
+pub fn threads_per_package() -> Option<u16> {
+    let topology_iter = get_topology_iterator();
+    let mut t_per_package = None;
+    for level in topology_iter {
+        if let Some(t_per_package) = t_per_package {
+            assert!(t_per_package <= level.processors())
+        }
+        t_per_package = Some(level.processors())
+    }
+    t_per_package
+}
+
+pub fn core_per_package() -> u16 {
+    let topology_iter = get_topology_iterator();
+    let mut t_per_core = None;
+    let mut t_per_package = None;
+    for level in topology_iter {
+        //println!("{:?}", level);
+        match level.level_type() {
+            TopologyType::SMT => {
+                assert_eq!(t_per_core, None);
+                t_per_core = Some(level.processors());
+            }
+            _ => { // TODO identify the right level ?
+                if let Some(t_per_package) = t_per_package {
+                    assert!(t_per_package <= level.processors())
+                }
+                // Or change the API to enable the user to specify the topology level to use according to the CPU micro-arch.
+                t_per_package = Some(level.processors())
+            }
+        }
+    }
+    if let Some(t_per_core) = t_per_core {
+        if let Some(t_per_package) = t_per_package {
+            if t_per_package % t_per_core == 0 {
+                return t_per_package / t_per_core;
+            }
+        }
+    }
+    0
+}