Linux und Memory

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Memory Management

$ cat /proc/meminfo
MemTotal:       32350736 kB
MemFree:         5046320 kB
MemAvailable:   22074652 kB
Buffers:          412328 kB
Cached:         17548704 kB
SwapCached:        22364 kB
Active:          5359816 kB
Inactive:       19629184 kB
Active(anon):    4108888 kB
Inactive(anon):  4211868 kB
Active(file):    1250928 kB
Inactive(file): 15417316 kB
Unevictable:      584908 kB
Mlocked:           27300 kB
SwapTotal:       8388604 kB
SwapFree:        8251388 kB
Zswap:                 0 kB
Zswapped:              0 kB
Dirty:               404 kB
Writeback:             0 kB
AnonPages:       7590884 kB
Mapped:          1591320 kB
Shmem:           1284036 kB
KReclaimable:     826852 kB
Slab:            1309168 kB
SReclaimable:     826852 kB
SUnreclaim:       482316 kB
KernelStack:       34320 kB
PageTables:       101448 kB
SecPageTables:         0 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    24563972 kB
Committed_AS:   25914404 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      145588 kB
VmallocChunk:          0 kB
Percpu:            49152 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
ShmemHugePages:   860160 kB
ShmemPmdMapped:        0 kB
FileHugePages:         0 kB
FilePmdMapped:         0 kB
Unaccepted:            0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
Hugetlb:               0 kB
DirectMap4k:      369856 kB
DirectMap2M:    12742656 kB
DirectMap1G:    19922944 kB

Transparent Hugepage (THP)

• https://docs.kernel.org/admin-guide/mm/transhuge.html
• https://www.percona.com/blog/transparent-huge-pages-refresher/
• https://blogs.oracle.com/exadata/huge-pages-or-transparent-huge-pages-in-context-of-exadata
• https://oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64
• https://stackoverflow.com/questions/16072389/how-do-i-enable-transparent-huge-pages-by-default-on-ubuntu
• https://www.pingcap.com/blog/transparent-huge-pages-why-we-disable-it-for-databases/
• https://utcc.utoronto.ca/~cks/space/blog/linux/TransparentHugepagesBadLuck
• https://help.splunk.com/en/splunk-enterprise/release-notes-and-updates/release-notes/9.2/known-issues-for-this-release/transparent-huge-memory-pages-and-splunk-performance
• https://community.intersystems.com/post/linux-transparent-hugepages-and-impact-intersystems-iris
• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/performance_tuning_guide/s-memory-transhuge
• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/performance_tuning_guide/sect-red_hat_enterprise_linux-performance_tuning_guide-configuring_transparent_huge_pages

Huge pages

• https://smalldatum.blogspot.com/2024/10/how-to-run-mysql-with-text-in-huge-pages.html
• https://stormatics.tech/blogs/configuring-linux-huge-pages-for-postgresql
• https://smalldatum.blogspot.com/2023/03/huge-pages-with-postgres-innodb-better.html
• https://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt
• https://smalldatum.blogspot.com/2025/10/measuring-scaleup-for-postgres-180-with.html
• https://www.percona.com/blog/why-linux-hugepages-are-super-important-for-database-servers-a-case-with-postgresql/
• https://docs.kernel.org/admin-guide/mm/transhuge.html
• https://wiki.debian.org/Hugepages
• https://events.linuxfoundation.org/wp-content/uploads/2022/03/Huge-Page-Concepts.pdf
• https://www.pythian.com/blog/technical-track/performance-tuning-hugepages-in-linux
• https://docs.oracle.com/en/database/oracle/oracle-database/19/ladbi/configuring_hugepages.html
• https://oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64
• https://www.kernel.org/doc/html/v5.0/admin-guide/mm/hugetlbpage.html
• https://rigtorp.se/hugepages/
• https://www.reddit.com/r/linux4noobs/comments/11h2mdv/what_is_hugepages/
• https://www.netdata.cloud/blog/understanding-huge-pages/
• https://stackoverflow.com/questions/72522360/why-doesnt-the-linux-kernel-use-huge-pages
• https://unix.stackexchange.com/questions/167451/how-to-monitor-use-of-huge-pages-per-process
• https://medium.com/@getpagespeed/linux-huge-pages-and-web-performance-24df3068a644
• https://serverfault.com/questions/898746/how-to-know-if-my-servers-should-use-huge-pages-memory-page-size
• https://docs.openstack.org/nova/pike/admin/huge-pages.html
• https://www.evanjones.ca/hugepages-are-a-good-idea.html
• https://joelsiks.com/posts/linux-huge-pages/
• https://serverfault.com/questions/438463/linux-huge-pages-usage-accounting
• https://www.baeldung.com/linux/huge-pages-management
• https://docs.arenadata.io/en/ADPG/current/how-to/enable-huge-pages.html
• https://docs.redhat.com/en/documentation/openshift_container_platform/4.2/html/scalability_and_performance/what-huge-pages-do-and-how-they-are-consumed
• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/performance_tuning_guide/s-memory-transhuge
• https://dev.mysql.com/doc/refman/9.1/en/large-page-support.html

Linux Memory Allocators

• https://docs.kernel.org/core-api/memory-allocation.html
• https://stackoverflow.com/questions/29056097/how-does-linux-allocate-memory-for-its-physical-allocator
• https://blogs.oracle.com/linux/linux-slub-allocator-internals-and-debugging-1
• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux_for_real_time/7/html/reference_guide/chap-memory_allocation
• https://github.com/emeryberger/Hoard
• https://syst3mfailure.io/linux-page-allocator/
• http://www.malloc.de/papers/malloc-slides.html
• https://sam4k.com/linternals-memory-allocators-part-1/
• https://www.kernel.org/doc/html/v5.8/core-api/memory-allocation.html
• https://www.marcusfolkesson.se/blog/contiguous-memory-allocator/
• https://www.linuxjournal.com/content/linux-memory-management-understanding-page-tables-swapping-and-memory-allocation
• https://dev.to/frosnerd/libmalloc-jemalloc-tcmalloc-mimalloc-exploring-different-memory-allocators-4lp3
• Alexey Stroganov, Percona, 2012-07-05: Impact of memory allocators on MySQL performance
• Alexey Stroganov, Percona, 2013-03-08: MySQL performance: Impact of memory allocators (Part 2)
• Mark Callaghan, SmallDatum. 2017-11-20: Concurrent large allocations: glibc malloc, jemalloc and tcmalloc
• Dominik Durner, Viktor Leis, Thomas Neumann, Technische Universität München, 2019: Experimental Study of Memory Allocation for High-Performance Query Processing, lokale Kopie
• Ameziane Hamlat, on atlassian.net, 2024-01-18: Reduce Memory usage by choosing a different low level allocator

glibc

• glibc malloc Website
• glibc malloc Wiki
• glibc Release Notes
• Arm Heap Exploitation, Part 1: Understanding the Glibc Heap Implementation
• Arm Heap Exploitation, Part 2: Understanding the GLIBC Heap Implementation
• Brice Dutheil, 2021-01-22: Handling native memory fragmentation of glibc

jemalloc

• jemalloc Source Code, jemalloc Website
• Jason Evans, 2025-06-12: jemalloc Postmortem
• Zac Policzer, LinkedIn Engineering Blog, 2021-01-28: Taming memory fragmentation in Venice with Jemalloc
• StackOverflow, 2012-11: CPU and memory usage of jemalloc as compared to glibc malloc
• Psi Mankoski, Aerospike on High Scalability, 2015-03-17: In-Memory Computing at Aerospike Scale: When to Choose and How to Effectively Use JEMalloc

tcmalloc

• https://github.com/google/tcmalloc
• https://google.github.io/tcmalloc/overview.html