Commit 3cdd868e authored by Changbin Du's avatar Changbin Du Committed by Jonathan Corbet

trace doc: convert trace/events-kmem.txt to rst format

This converts the plain text documentation to reStructuredText format and
add it into Sphinx TOC tree. No essential content change.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarChangbin Du <changbin.du@intel.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 73d98127
Subsystem Trace Points: kmem ============================
Subsystem Trace Points: kmem
============================
The kmem tracing system captures events related to object and page allocation The kmem tracing system captures events related to object and page allocation
within the kernel. Broadly speaking there are five major subheadings. within the kernel. Broadly speaking there are five major subheadings.
o Slab allocation of small objects of unknown type (kmalloc) - Slab allocation of small objects of unknown type (kmalloc)
o Slab allocation of small objects of known type - Slab allocation of small objects of known type
o Page allocation - Page allocation
o Per-CPU Allocator Activity - Per-CPU Allocator Activity
o External Fragmentation - External Fragmentation
This document describes what each of the tracepoints is and why they This document describes what each of the tracepoints is and why they
might be useful. might be useful.
1. Slab allocation of small objects of unknown type 1. Slab allocation of small objects of unknown type
=================================================== ===================================================
kmalloc call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s ::
kmalloc_node call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s node=%d
kfree call_site=%lx ptr=%p kmalloc call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s
kmalloc_node call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s node=%d
kfree call_site=%lx ptr=%p
Heavy activity for these events may indicate that a specific cache is Heavy activity for these events may indicate that a specific cache is
justified, particularly if kmalloc slab pages are getting significantly justified, particularly if kmalloc slab pages are getting significantly
...@@ -27,9 +31,11 @@ the allocation sites were. ...@@ -27,9 +31,11 @@ the allocation sites were.
2. Slab allocation of small objects of known type 2. Slab allocation of small objects of known type
================================================= =================================================
kmem_cache_alloc call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s ::
kmem_cache_alloc_node call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s node=%d
kmem_cache_free call_site=%lx ptr=%p kmem_cache_alloc call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s
kmem_cache_alloc_node call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s node=%d
kmem_cache_free call_site=%lx ptr=%p
These events are similar in usage to the kmalloc-related events except that These events are similar in usage to the kmalloc-related events except that
it is likely easier to pin the event down to a specific cache. At the time it is likely easier to pin the event down to a specific cache. At the time
...@@ -38,10 +44,12 @@ but the call_site can usually be used to extrapolate that information. ...@@ -38,10 +44,12 @@ but the call_site can usually be used to extrapolate that information.
3. Page allocation 3. Page allocation
================== ==================
mm_page_alloc page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s ::
mm_page_alloc_zone_locked page=%p pfn=%lu order=%u migratetype=%d cpu=%d percpu_refill=%d
mm_page_free page=%p pfn=%lu order=%d mm_page_alloc page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s
mm_page_free_batched page=%p pfn=%lu order=%d cold=%d mm_page_alloc_zone_locked page=%p pfn=%lu order=%u migratetype=%d cpu=%d percpu_refill=%d
mm_page_free page=%p pfn=%lu order=%d
mm_page_free_batched page=%p pfn=%lu order=%d cold=%d
These four events deal with page allocation and freeing. mm_page_alloc is These four events deal with page allocation and freeing. mm_page_alloc is
a simple indicator of page allocator activity. Pages may be allocated from a simple indicator of page allocator activity. Pages may be allocated from
...@@ -65,8 +73,10 @@ contention on the zone->lru_lock. ...@@ -65,8 +73,10 @@ contention on the zone->lru_lock.
4. Per-CPU Allocator Activity 4. Per-CPU Allocator Activity
============================= =============================
mm_page_alloc_zone_locked page=%p pfn=%lu order=%u migratetype=%d cpu=%d percpu_refill=%d ::
mm_page_pcpu_drain page=%p pfn=%lu order=%d cpu=%d migratetype=%d
mm_page_alloc_zone_locked page=%p pfn=%lu order=%u migratetype=%d cpu=%d percpu_refill=%d
mm_page_pcpu_drain page=%p pfn=%lu order=%d cpu=%d migratetype=%d
In front of the page allocator is a per-cpu page allocator. It exists only In front of the page allocator is a per-cpu page allocator. It exists only
for order-0 pages, reduces contention on the zone->lock and reduces the for order-0 pages, reduces contention on the zone->lock and reduces the
...@@ -92,7 +102,9 @@ can be allocated and freed on the same CPU through some algorithm change. ...@@ -92,7 +102,9 @@ can be allocated and freed on the same CPU through some algorithm change.
5. External Fragmentation 5. External Fragmentation
========================= =========================
mm_page_alloc_extfrag page=%p pfn=%lu alloc_order=%d fallback_order=%d pageblock_order=%d alloc_migratetype=%d fallback_migratetype=%d fragmenting=%d change_ownership=%d ::
mm_page_alloc_extfrag page=%p pfn=%lu alloc_order=%d fallback_order=%d pageblock_order=%d alloc_migratetype=%d fallback_migratetype=%d fragmenting=%d change_ownership=%d
External fragmentation affects whether a high-order allocation will be External fragmentation affects whether a high-order allocation will be
successful or not. For some types of hardware, this is important although successful or not. For some types of hardware, this is important although
......
...@@ -13,3 +13,4 @@ Linux Tracing Technologies ...@@ -13,3 +13,4 @@ Linux Tracing Technologies
uprobetracer uprobetracer
tracepoints tracepoints
events events
events-kmem
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