search for: find_get_page

...: minor fault optimization. On of the challenges of hva is the cost for the state transitions. If the cost gets too big the whole concept of page state information is in question. Therefore it is very important to avoid the state transitions for minor faults. Why change the page state to stable in find_get_page and back in page_add_anon_rmap/page_add_file_rmap if the discarded pages can be handled by the discard fault handler? If the page is in page/swap cache just map it even if it is already discarded. The first access to the page will cause a discard fault which needs to be able to deal with this kind...

...: minor fault optimization. On of the challenges of hva is the cost for the state transitions. If the cost gets too big the whole concept of page state information is in question. Therefore it is very important to avoid the state transitions for minor faults. Why change the page state to stable in find_get_page and back in page_add_anon_rmap/page_add_file_rmap if the discarded pages can be handled by the discard fault handler? If the page is in page/swap cache just map it even if it is already discarded. The first access to the page will cause a discard fault which needs to be able to deal with this kind...

A user has encountered a NULL pointer kernel oops in btrfs when encountering media errors. The problem has been identified as an unhandled NULL pointer returned from find_get_page(). This modification simply checks for a NULL page, and returns with an error if found (the extent_range_uptodate() function returns 1 on errors). After testing this patch, the user reported that the error with the NULL pointer oops was solved. However, there is still a remaining problem with a t...

...m> From: Himanshu Raj <rhim@cc.gatech.edu> [patch 4/9] Guest page hinting: volatile swap cache. The volatile page state can be used for anonymous pages as well, if they have been added to the swap cache and the swap write is finished. The tricky bit is in free_swap_and_cache. The call to find_get_page dead-locks with the discard handler. If the page has been discarded find_get_page will try to remove it. To do that it needs the page table lock of all mappers but one is held by the caller of free_swap_and_cache. A special variant of find_get_page is needed that does not check the page state and r...

...m> From: Himanshu Raj <rhim@cc.gatech.edu> [patch 4/9] Guest page hinting: volatile swap cache. The volatile page state can be used for anonymous pages as well, if they have been added to the swap cache and the swap write is finished. The tricky bit is in free_swap_and_cache. The call to find_get_page dead-locks with the discard handler. If the page has been discarded find_get_page will try to remove it. To do that it needs the page table lock of all mappers but one is held by the caller of free_swap_and_cache. A special variant of find_get_page is needed that does not check the page state and r...

...ge_cache_async_readahead(inode->i_mapping, + ra, NULL, page, index, + last_index + 1 - index); } if (!PageUptodate(page)) { diff --git a/mm/filemap.c b/mm/filemap.c index 3843445..d703224 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1113,8 +1113,7 @@ find_page: page = find_get_page(mapping, index); if (unlikely(page == NULL)) goto no_cached_page; - } - if (PageReadahead(page)) { + } else if (PageReadahead(page)) { page_cache_async_readahead(mapping, ra, filp, page, index, last_index - index); -- 1.7.12.3 -- To unsubscribe from this list: send the...

Greetings, after Carsten pitched CMM2 on the kvm mini summit here is a repost of version 5 of the guest page hinting patches. The code is still the same but has been adapted to the latest git level. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.

Greetings, after Carsten pitched CMM2 on the kvm mini summit here is a repost of version 5 of the guest page hinting patches. The code is still the same but has been adapted to the latest git level. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.

After way to many months here is the fifth version of the guest page hinting patches. Compared to version four a few improvements have been added: - Avoid page_host_discards() calls outside of page-states.h - The discard list is now implemented via the page_free_discarded hook and architecture specific code. - PG_state_change page flag has been replaced with architecture specficic

After way to many months here is the fifth version of the guest page hinting patches. Compared to version four a few improvements have been added: - Avoid page_host_discards() calls outside of page-states.h - The discard list is now implemented via the page_free_discarded hook and architecture specific code. - PG_state_change page flag has been replaced with architecture specficic

...3 localhost kernel: [wake_bit_function+0/96] wake_bit_function+0x0/0x60 Nov 1 13:52:13 localhost kernel: [page_cache_readahead+218/720] page_cache_readahead+0xda/0x2d0 Nov 1 13:52:13 localhost kernel: [wake_bit_function+0/96] wake_bit_function+0x0/0x60 Nov 1 13:52:13 localhost kernel: [find_get_page+53/128] find_get_page+0x35/0x80 Nov 1 13:52:13 localhost kernel: [do_generic_mapping_read +1207/1472] do_generic_mapping_read+0x4b7/0x5c0 Nov 1 13:52:13 localhost kernel: [__generic_file_aio_read+514/576] __generic_file_aio_read+0x202/0x240 Nov 1 13:52:13 localhost kernel: [file_read_act...

...age is already discarded. 10) The page map count is not equal to the page reference count - 1. The discard fault handler can remove the page cache reference and all mappers of a page. It cannot remove the page reference for any other user of the page. The transitions to stable are done by find_get_pages() and its variants, in get_user_pages if called with a pages parameter, by copy-on-write in do_wp_page, and by the early copy-on-write in do_no_page. To make enough pages discardable by the host an attempt to do the transition to volatile state is done when a page gets unlocked (unlock_page), when...

...age is already discarded. 10) The page map count is not equal to the page reference count - 1. The discard fault handler can remove the page cache reference and all mappers of a page. It cannot remove the page reference for any other user of the page. The transitions to stable are done by find_get_pages() and its variants, in get_user_pages if called with a pages parameter, by copy-on-write in do_wp_page, and by the early copy-on-write in do_no_page. To make enough pages discardable by the host an attempt to do the transition to volatile state is done when a page gets unlocked (unlock_page), when...

...c01306b9>] autoremove_wake_function+0x0/0x37 [<c01306b9>] autoremove_wake_function+0x0/0x37 [<c0278ff7>] sock_sendmsg+0xe5/0x100 [<c01cd8be>] copy_from_user+0x33/0x69 [<c027913f>] sys_sendmsg+0x12d/0x243 [<c02e2564>] _read_unlock_irq+0x5/0x7 [<c013fb2b>] find_get_page+0x37/0x42 [<c01423dd>] filemap_nopage+0x30c/0x3a3 [<c014bb99>] __handle_mm_fault+0x21c/0x943 [<c02e24c5>] _spin_unlock_bh+0x5/0xd [<c027b475>] sock_setsockopt+0x63/0x59d [<c0151801>] anon_vma_prepare+0x1b/0xcb [<c027a2ea>] sys_socketcall+0x24f/0x271 [<c...

...tart_io+0x77/0xdc [cciss] [<f88bf63e>] do_cciss_request+0x32c/0x337 [cciss] [<f88ccff0>] __split_bio+0x408/0x418 [dm_mod] [<f88cd6a6>] dm_request+0xce/0xd4 [dm_mod] [<c04d6a81>] generic_make_request+0x248/0x258 [<c04d8734>] submit_bio+0xbf/0xc5 [<c04548e2>] find_get_page+0x18/0x38 [<c04719ad>] __find_get_block_slow+0xfb/0x105 [<c0471cea>] __find_get_block+0x15c/0x166 [<c0471cea>] __find_get_block+0x15c/0x166 [<c0471d24>] __getblk+0x30/0x270 [<f885a485>] journal_cancel_revoke+0x8a/0x96 [jbd] [<f885a472>] journal_cancel_revok...

...mic 41182 6.0189 vmlinux-2.6.16.46-0.10-bigsmp page_fault 36425 5.3236 vmlinux-2.6.16.46-0.10-bigsmp copy_page_range 34533 5.0471 vmlinux-2.6.16.46-0.10-bigsmp unmap_vmas 32155 4.6996 vmlinux-2.6.16.46-0.10-bigsmp __handle_mm_fault 30848 4.5085 vmlinux-2.6.16.46-0.10-bigsmp find_get_page 28589 4.1784 vmlinux-2.6.16.46-0.10-bigsmp page_remove_rmap On pure HTML workload, I find little performance gap between domain 0 and Native, and neither so much Memory and Page operation. Is the Domain 0 performance for CGI degration because of Xen Memory and Page ineffiencency? Any hints or...

...mic 41182 6.0189 vmlinux-2.6.16.46-0.10-bigsmp page_fault 36425 5.3236 vmlinux-2.6.16.46-0.10-bigsmp copy_page_range 34533 5.0471 vmlinux-2.6.16.46-0.10-bigsmp unmap_vmas 32155 4.6996 vmlinux-2.6.16.46-0.10-bigsmp __handle_mm_fault 30848 4.5085 vmlinux-2.6.16.46-0.10-bigsmp find_get_page 28589 4.1784 vmlinux-2.6.16.46-0.10-bigsmp page_remove_rmap On pure HTML workload, I find little performance gap between domain 0 and Native, and neither so much Memory and Page operation. Is the Domain 0 performance for CGI degration because of Xen Memory and Page ineffiencency? Any hints or...

...the kernel it is stuck in, and here is the output of opreport -l vmlinux (top scores only): CPU: CPU with timer interrupt, speed 0 MHz (estimated) Profiling through timer interrupt samples % symbol name 21117 36.5340 default_idle 3850 6.6608 __copy_from_user_ll 3108 5.3771 find_get_page 1707 2.9532 __copy_user_intel 1580 2.7335 __might_sleep 1356 2.3460 handle_IRQ_event 1323 2.2889 __copy_to_user_ll 1168 2.0207 __find_get_block_slow 1134 1.9619 __find_get_block 1093 1.8910 finish_task_switch 963 1.6661 bh_lru_install 638 1.103...

...kup_tag+0x1a/0x21 [ 240.592954] [<ffffffff810b4577>] ? wait_on_page_writeback_range+0x69/0x11b [ 240.594403] [<ffffffff810b536e>] ? filemap_write_and_wait+0x26/0x32 [ 240.595563] [<ffffffffa02c0d35>] ? nfs_setattr+0xb9/0x117 [nfs] [ 240.596670] [<ffffffff810b3a0b>] ? find_get_page+0x1a/0x77 [ 240.598012] [<ffffffff810b3bb9>] ? lock_page+0x9/0x1f [ 240.598878] [<ffffffff810b41ee>] ? filemap_fault+0xb9/0x2f6 [ 240.599839] [<ffffffff810ca3c2>] ? __do_fault+0x38c/0x3c3 [ 240.601003] [<ffffffff810ee1ce>] ? do_sync_write+0xce/0x113 [ 240.602082] [...

...kup_tag+0x1a/0x21 [ 240.592954] [<ffffffff810b4577>] ? wait_on_page_writeback_range+0x69/0x11b [ 240.594403] [<ffffffff810b536e>] ? filemap_write_and_wait+0x26/0x32 [ 240.595563] [<ffffffffa02c0d35>] ? nfs_setattr+0xb9/0x117 [nfs] [ 240.596670] [<ffffffff810b3a0b>] ? find_get_page+0x1a/0x77 [ 240.598012] [<ffffffff810b3bb9>] ? lock_page+0x9/0x1f [ 240.598878] [<ffffffff810b41ee>] ? filemap_fault+0xb9/0x2f6 [ 240.599839] [<ffffffff810ca3c2>] ? __do_fault+0x38c/0x3c3 [ 240.601003] [<ffffffff810ee1ce>] ? do_sync_write+0xce/0x113 [ 240.602082] [...