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netfs: Speed up buffered reading

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Improve the efficiency of buffered reads in a number of ways:

 (1) Overhaul the algorithm in general so that it's a lot more compact and
     split the read submission code between buffered and unbuffered
     versions.  The unbuffered version can be vastly simplified.

 (2) Read-result collection is handed off to a work queue rather than being
     done in the I/O thread.  Multiple subrequests can be processes
     simultaneously.

 (3) When a subrequest is collected, any folios it fully spans are
     collected and "spare" data on either side is donated to either the
     previous or the next subrequest in the sequence.

Notes:

 (*) Readahead expansion is massively slows down fio, presumably because it
     causes a load of extra allocations, both folio and xarray, up front
     before RPC requests can be transmitted.

 (*) RDMA with cifs does appear to work, both with SIW and RXE.

 (*) PG_private_2-based reading and copy-to-cache is split out into its own
     file and altered to use folio_queue.  Note that the copy to the cache
     now creates a new write transaction against the cache and adds the
     folios to be copied into it.  This allows it to use part of the
     writeback I/O code.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Howells
2024-09-12 12:20:41 +02:00
committed by Christian Brauner
parent 2e45b92297
commit ee4cdf7ba8
28 changed files with 2063 additions and 475 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/trace/events/netfs.h
+98 -5
View File
@@ -20,6 +20,7 @@
EM(netfs_read_trace_expanded, "EXPANDED ") \
EM(netfs_read_trace_readahead, "READAHEAD") \
EM(netfs_read_trace_readpage, "READPAGE ") \
EM(netfs_read_trace_read_gaps, "READ-GAPS") \
EM(netfs_read_trace_prefetch_for_write, "PREFETCHW") \
E_(netfs_read_trace_write_begin, "WRITEBEGN")
@@ -33,12 +34,14 @@
#define netfs_rreq_origins \
EM(NETFS_READAHEAD, "RA") \
EM(NETFS_READPAGE, "RP") \
EM(NETFS_READ_GAPS, "RG") \
EM(NETFS_READ_FOR_WRITE, "RW") \
EM(NETFS_DIO_READ, "DR") \
EM(NETFS_WRITEBACK, "WB") \
EM(NETFS_WRITETHROUGH, "WT") \
EM(NETFS_UNBUFFERED_WRITE, "UW") \
E_(NETFS_DIO_WRITE, "DW")
EM(NETFS_DIO_WRITE, "DW") \
E_(NETFS_PGPRIV2_COPY_TO_CACHE, "2C")
#define netfs_rreq_traces \
EM(netfs_rreq_trace_assess, "ASSESS ") \
@@ -69,15 +72,25 @@
E_(NETFS_INVALID_WRITE, "INVL")
#define netfs_sreq_traces \
EM(netfs_sreq_trace_add_donations, "+DON ") \
EM(netfs_sreq_trace_added, "ADD ") \
EM(netfs_sreq_trace_clear, "CLEAR") \
EM(netfs_sreq_trace_discard, "DSCRD") \
EM(netfs_sreq_trace_donate_to_prev, "DON-P") \
EM(netfs_sreq_trace_donate_to_next, "DON-N") \
EM(netfs_sreq_trace_download_instead, "RDOWN") \
EM(netfs_sreq_trace_fail, "FAIL ") \
EM(netfs_sreq_trace_free, "FREE ") \
EM(netfs_sreq_trace_hit_eof, "EOF ") \
EM(netfs_sreq_trace_io_progress, "IO ") \
EM(netfs_sreq_trace_limited, "LIMIT") \
EM(netfs_sreq_trace_prepare, "PREP ") \
EM(netfs_sreq_trace_prep_failed, "PRPFL") \
EM(netfs_sreq_trace_resubmit_short, "SHORT") \
EM(netfs_sreq_trace_progress, "PRGRS") \
EM(netfs_sreq_trace_reprep_failed, "REPFL") \
EM(netfs_sreq_trace_retry, "RETRY") \
EM(netfs_sreq_trace_short, "SHORT") \
EM(netfs_sreq_trace_split, "SPLIT") \
EM(netfs_sreq_trace_submit, "SUBMT") \
EM(netfs_sreq_trace_terminated, "TERM ") \
EM(netfs_sreq_trace_write, "WRITE") \
@@ -118,7 +131,7 @@
EM(netfs_sreq_trace_new, "NEW ") \
EM(netfs_sreq_trace_put_cancel, "PUT CANCEL ") \
EM(netfs_sreq_trace_put_clear, "PUT CLEAR ") \
EM(netfs_sreq_trace_put_discard, "PUT DISCARD") \
EM(netfs_sreq_trace_put_consumed, "PUT CONSUME") \
EM(netfs_sreq_trace_put_done, "PUT DONE ") \
EM(netfs_sreq_trace_put_failed, "PUT FAILED ") \
EM(netfs_sreq_trace_put_merged, "PUT MERGED ") \
@@ -138,6 +151,7 @@
EM(netfs_flush_content, "flush") \
EM(netfs_streaming_filled_page, "mod-streamw-f") \
EM(netfs_streaming_cont_filled_page, "mod-streamw-f+") \
EM(netfs_folio_trace_abandon, "abandon") \
EM(netfs_folio_trace_cancel_copy, "cancel-copy") \
EM(netfs_folio_trace_clear, "clear") \
EM(netfs_folio_trace_clear_cc, "clear-cc") \
@@ -154,7 +168,11 @@
EM(netfs_folio_trace_mkwrite_plus, "mkwrite+") \
EM(netfs_folio_trace_not_under_wback, "!wback") \
EM(netfs_folio_trace_put, "put") \
EM(netfs_folio_trace_read, "read") \
EM(netfs_folio_trace_read_done, "read-done") \
EM(netfs_folio_trace_read_gaps, "read-gaps") \
EM(netfs_folio_trace_read_put, "read-put") \
EM(netfs_folio_trace_read_unlock, "read-unlock") \
EM(netfs_folio_trace_redirtied, "redirtied") \
EM(netfs_folio_trace_store, "store") \
EM(netfs_folio_trace_store_copy, "store-copy") \
@@ -167,6 +185,12 @@
EM(netfs_contig_trace_jump, "-->JUMP-->") \
E_(netfs_contig_trace_unlock, "Unlock")
#define netfs_donate_traces \
EM(netfs_trace_donate_tail_to_prev, "tail-to-prev") \
EM(netfs_trace_donate_to_prev, "to-prev") \
EM(netfs_trace_donate_to_next, "to-next") \
E_(netfs_trace_donate_to_deferred_next, "defer-next")
#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
@@ -184,6 +208,7 @@ enum netfs_rreq_ref_trace { netfs_rreq_ref_traces } __mode(byte);
enum netfs_sreq_ref_trace { netfs_sreq_ref_traces } __mode(byte);
enum netfs_folio_trace { netfs_folio_traces } __mode(byte);
enum netfs_collect_contig_trace { netfs_collect_contig_traces } __mode(byte);
enum netfs_donate_trace { netfs_donate_traces } __mode(byte);
#endif
@@ -206,6 +231,7 @@ netfs_rreq_ref_traces;
netfs_sreq_ref_traces;
netfs_folio_traces;
netfs_collect_contig_traces;
netfs_donate_traces;
/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -226,6 +252,7 @@ TRACE_EVENT(netfs_read,
TP_STRUCT__entry(
__field(unsigned int, rreq )
__field(unsigned int, cookie )
__field(loff_t, i_size )
__field(loff_t, start )
__field(size_t, len )
__field(enum netfs_read_trace, what )
@@ -235,18 +262,19 @@ TRACE_EVENT(netfs_read,
TP_fast_assign(
__entry->rreq = rreq->debug_id;
__entry->cookie = rreq->cache_resources.debug_id;
__entry->i_size = rreq->i_size;
__entry->start = start;
__entry->len = len;
__entry->what = what;
__entry->netfs_inode = rreq->inode->i_ino;
),
TP_printk("R=%08x %s c=%08x ni=%x s=%llx %zx",
TP_printk("R=%08x %s c=%08x ni=%x s=%llx l=%zx sz=%llx",
__entry->rreq,
__print_symbolic(__entry->what, netfs_read_traces),
__entry->cookie,
__entry->netfs_inode,
__entry->start, __entry->len)
__entry->start, __entry->len, __entry->i_size)
);
TRACE_EVENT(netfs_rreq,
@@ -651,6 +679,71 @@ TRACE_EVENT(netfs_collect_stream,
__entry->collected_to, __entry->front)
);
TRACE_EVENT(netfs_progress,
TP_PROTO(const struct netfs_io_subrequest *subreq,
unsigned long long start, size_t avail, size_t part),
TP_ARGS(subreq, start, avail, part),
TP_STRUCT__entry(
__field(unsigned int, rreq)
__field(unsigned int, subreq)
__field(unsigned int, consumed)
__field(unsigned int, transferred)
__field(unsigned long long, f_start)
__field(unsigned int, f_avail)
__field(unsigned int, f_part)
__field(unsigned char, slot)
),
TP_fast_assign(
__entry->rreq = subreq->rreq->debug_id;
__entry->subreq = subreq->debug_index;
__entry->consumed = subreq->consumed;
__entry->transferred = subreq->transferred;
__entry->f_start = start;
__entry->f_avail = avail;
__entry->f_part = part;
__entry->slot = subreq->curr_folioq_slot;
),
TP_printk("R=%08x[%02x] s=%llx ct=%x/%x pa=%x/%x sl=%x",
__entry->rreq, __entry->subreq, __entry->f_start,
__entry->consumed, __entry->transferred,
__entry->f_part, __entry->f_avail, __entry->slot)
);
TRACE_EVENT(netfs_donate,
TP_PROTO(const struct netfs_io_request *rreq,
const struct netfs_io_subrequest *from,
const struct netfs_io_subrequest *to,
size_t amount,
enum netfs_donate_trace trace),
TP_ARGS(rreq, from, to, amount, trace),
TP_STRUCT__entry(
__field(unsigned int, rreq)
__field(unsigned int, from)
__field(unsigned int, to)
__field(unsigned int, amount)
__field(enum netfs_donate_trace, trace)
),
TP_fast_assign(
__entry->rreq = rreq->debug_id;
__entry->from = from->debug_index;
__entry->to = to ? to->debug_index : -1;
__entry->amount = amount;
__entry->trace = trace;
),
TP_printk("R=%08x[%02x] -> [%02x] %s am=%x",
__entry->rreq, __entry->from, __entry->to,
__print_symbolic(__entry->trace, netfs_donate_traces),
__entry->amount)
);
#undef EM
#undef E_
#endif /* _TRACE_NETFS_H */