From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id F14A68D0039 for ; Fri, 18 Feb 2011 10:49:12 -0500 (EST) Subject: mm: mm_struct remove 16 bytes of alignment padding on 64 bit builds From: Richard Kennedy Content-Type: text/plain; charset="UTF-8" Date: Fri, 18 Feb 2011 15:49:07 +0000 Message-ID: <1298044147.2071.5.camel@castor.rsk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm , lkml Reorder mm_struct to remove 16 bytes of alignment padding on 64 bit builds. On my config this shrinks mm_struct by enough to fit in one fewer cache lines and allows more objects per slab in mm_struct kmem_cache under SLUB. slabinfo before patch :- Sizes (bytes) Slabs -------------------------------- Object : 848 Total : 9 SlabObj: 896 Full : 2 SlabSiz: 16384 Partial: 5 Loss : 48 CpuSlab: 2 Align : 64 Objects: 18 slabinfo after :- Sizes (bytes) Slabs -------------------------------- Object : 832 Total : 7 SlabObj: 832 Full : 2 SlabSiz: 16384 Partial: 3 Loss : 0 CpuSlab: 2 Align : 64 Objects: 19 Signed-off-by: Richard Kennedy --- patch against v2.6.38-rc4 compiled & tested on x86_64 regards Richard diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 26bc4e2..02aa561 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -237,8 +237,9 @@ struct mm_struct { atomic_t mm_users; /* How many users with user space? */ atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */ int map_count; /* number of VMAs */ - struct rw_semaphore mmap_sem; + spinlock_t page_table_lock; /* Protects page tables and some counters */ + struct rw_semaphore mmap_sem; struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung * together off init_mm.mmlist, and are protected @@ -281,6 +282,9 @@ struct mm_struct { unsigned int token_priority; unsigned int last_interval; + /* How many tasks sharing this mm are OOM_DISABLE */ + atomic_t oom_disable_count; + unsigned long flags; /* Must use atomic bitops to access the bits */ struct core_state *core_state; /* coredumping support */ @@ -313,8 +317,6 @@ struct mm_struct { #ifdef CONFIG_TRANSPARENT_HUGEPAGE pgtable_t pmd_huge_pte; /* protected by page_table_lock */ #endif - /* How many tasks sharing this mm are OOM_DISABLE */ - atomic_t oom_disable_count; }; /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org